Internet Basics Thursday, November 20, 2008

Transcription

1 Internet Basics Thursday, November 20, 2008 Welcome to Internet Basics, the first section of the Basic Networking course of the online Allworx Reseller technical training. This course provides general information intended to familiarize students with basic networking technology. While it includes material that is specific to installing the Allworx system, most of the material applies to all networks. Unlike traditional analog phone systems, Allworx PBXs and Allworx phones are connected together using a standard computer network. Understanding computer networking is necessary to be able to install and configure Allworx systems at customer sites. This Basic Networking module provides the background necessary for you to understand the connections and settings that are required for the installation. If you are experienced in networking technology, you may find this module to be a useful review. However, if you are new to computer networks, you will find that the information in this module is vital to understanding the Allworx-specific training modules that follow. So on to Internet Basics Page 1

2 Internet Basics Thursday, November 20, 2008 So what is the Internet? The Internet is an enormous computer network that spans the globe. It is constructed from many smaller networks that are connected together. These networks are owned by many different companies such as AT&T, Verizon, and Sprint. These companies cooperate to provide the World Wide Web. Before getting into the details, we should pass along some concepts and terminology that you will hear throughout the presentation. The devices that connect the networks together are called Routers. Routers facilitate the Internet by forwarding messages that are originated in one part of the Internet to the next network in the path to the messages' intended destination. The messages that are communicated across the Internet use a network language or protocol called IP. This stands for Internet Protocol. This protocol is used for many things on the Internet including sending and web pages. For users of Voice over IP phones and IP-PBXs such as make up the Allworx Family of products, telephone call audio is transmitted over the Internet in IP messages. Computers on the Internet are known by their IP addresses. It is important for you to understand the system for assigning and using IP addresses. The details of IP addressing will be covered in this module. Page 2

3 Internet Basics Thursday, November 20, 2008 Here is an example of one of the core networks of the Internet. UUNET is now Verizon. Its network spans the US and extends to other continents. that you send may sometimes be forwarded through this network to get to other parts of the country. Other similar networks connect to the Verizon network to make up the Internet. Page 3

4 Internet Basics Thursday, November 20, 2008 Here is a concept diagram of how the participating networks come together to form the Internet. The clouds in the middle of the diagram represent the larger networks that form the core of the Internet. Our example shows two different users that are connected to the Internet through their own Internet Service Providers: AOL and Comcast. Internet Service Providers (also known as ISPs) are the companies that you pay a monthly fee to for Internet service at your home or business. In this example, you (we ll call you Chris) are sending an message to your friend Pat on the other side of the country. Your would go through your Internet connection to your ISP s network, in this case, Comcast. From there, it would be forwarded to one of the large core networks, such as Verizon. Routers on these networks forward your to the next network along the path to the s destination. Eventually, your arrives at Pat s ISP s network, AOL. At this point it will be available for Pat to read. Page 4

5 Internet Basics Thursday, November 20, 2008 Microsoft Windows has a program that can display the path that messages take across the Internet. We can use it to see how a message would travel if you sent one from your PC to lets say, Allworx. The program is called traceroute. The traceroute command is normally used for debugging network problems. Even if you are not ready for start analyzing networks yet, trying this command now will be very useful. Running the command uses some other skills that are essential for working with the Allworx system. Also, the results provide an excellent illustration of the workings of the Internet. So be sure to try this command out for yourself, at the end of the presentation. However, if your PC is behind a firewall, the Microsoft tool may not display the full path through the internet. This can also occur if you are behind an Allworx server acting as a firewall. Page 5

6 Internet Basics Thursday, November 20, 2008 To run traceroute, first open a command window. To do this, using your mouse, click the start button in the lower left corner of the screen. Page 6

7 Internet Basics Thursday, November 20, 2008 Then click Run. Page 7

8 Internet Basics Thursday, November 20, 2008 The Run window will open. Type cmd then click OK. Page 8

9 Internet Basics Thursday, November 20, 2008 This brings up a Command window. From within the command window, you can run programs that do not appear in any Windows menus. In particular, some commands that involve networking must be run from within a command window. Installing Allworx systems requires that you be familiar with this technique. In the command window, type tracert, a space, then Then press the Enter key on your keyboard. This command sends a test message to the computer that hosts the Allworx website. The command window displays one line for each router that forwarded the message. In this case, the message passed through 17 networks on its way from the PC to the Allworx website. The time values indicate how long it took for the message to get to that router for each of three tries. The last column is the name or IP address of the router. Notice that the routers have unusual names but they sometimes provide a clue to which networks passed the message through. For instance, the message passed through one of the larger networks on the Internet, NTT. It also passed through one of the larger providers of Internet service to business, Verio. The numbers with periods are the IP addresses of the routers. We will cover IP addressing, later in this training section. Page 9

10 Internet Basics Thursday, November 20, 2008 Computer networks use numeric addresses to keep track of computers and other devices. Network messages use the intended recipient s IP address as their destination. Routers forward the messages based on the address. IP addresses are made up of four numbers, separated by periods. These are called octets. Each of the octets is a number between 0 and 254. Some IP addresses are intended to be used only within home or company networks. These are called Private IP addresses. All other addresses are called Public IP addresses and can be used on the Internet. There are systems in place to make sure that no two devices use the same public IP address. Whereas private IP addresses can be used by many PCs on their own networks. Page 10

11 Internet Basics Thursday, November 20, 2008 Public IP addresses are assigned by Internet Service Providers. ISPs like Comcast, Verizon, and AT&T are given ranges of public IP address that they parcel out to their customers. This system ensures that no two devices on the Internet have the same address. There are about four and a half billion addresses in the public IP address range. This may seem like a lot. However the Internet is worldwide and with so many devices that can connect to the Internet, we are running out of addresses. One way to economize on addresses is to allocate private IP addresses for internal use by companies. Page 11

12 Internet Basics Thursday, November 20, 2008 Within the range of possible IP addresses, some are reserved for internal use on company and home networks. As long as these addresses are not used on the Internet, many companies can use the same addresses. The allocation of these addresses on a company s network is controlled by the company. This allows computers to attach to networks without using public IP addresses. The private IP address ranges are listed here. In this list, the letter x indicates that any number between 0 and 254 can be used for that octet. On a side note, if an Allworx server is used to control a site s network, it uses the private IP address range for computers and phones on its network. Page 12

13 Internet Basics Thursday, November 20, 2008 We have already mentioned how routers on the Internet connect networks together and forward messages. They provide other functions, as well. To enable private IP addresses to be used, company networks must be isolated from the Internet by routers. The terminology for this separation is that the company network is called the Local Area Network or LAN. The other side of the router is called the Wide Area Network or WAN. The LAN and WAN are separate network interfaces. Each has its own IP address. When the WAN port is connected to the Internet, it must have a public IP address. The LAN side would have a private IP address. Not all routers connect directly to the Internet. Some connect one part of a company network to another. In such cases, the LAN and WAN might both have private IP addresses. Routers also perform Network Address Translation or NAT. This feature permits computers on the LAN that have private IP addresses to access the Internet. It prevents PCs with the same private IP address on different networks from conflicting with each other. Page 13

14 Internet Basics Thursday, November 20, 2008 Without NAT, computers on company networks would not be able to send or access Internet Websites. This is because other PCs might be using the same IP address. This would confuse the Internet routers that are responsible for forwarding messages. If the company has multiple public IP addresses, the router will temporarily assign one to each computer that accesses the Internet at one time. The router translates the private IP address of the local device to the public IP address to be used on the Internet. If there are not enough public IP addresses to go around, the router must use other more complex techniques. These techniques permit more than one local device to use a single public IP address, at the same time. The end result is that fewer public IP addresses are needed. Page 14

15 Internet Basics Thursday, November 20, 2008 This diagram depicts the interaction between the Internet and a company's LAN through a router. The network at the bottom has addresses in the private range. If computer #1 wanted to download Google s web page, it would send a website request through the router on its LAN. The router would see the request and realize that a change was required. The router knows that Google's web server will be sending the website information back to the source IP address of the download request. Since the source address of the request is a private address, the web server will not know where to send the website information. The router must change the source address from Computer #1 s private address ( ) to its own WAN address, Google would then send its web page information to the router's WAN address. It would be the router s job to remember that Computer #1 is the originator of the download. The router would then forward the web page to Computer #1 at its private IP address. Page 15

16 Internet Basics Thursday, November 20, 2008 Another important concept is that of domain names. Domain names are names that represent a computer on the Internet or on some private network. The most common domain names that you hear of are usually web servers on the Internet. Names like Google.com and Allworx.com are domain names. If you wish to access the web page from one of these servers, you can do so by typing the domain name into the address bar of a web browser. The domain name for a web server is synonymous with its IP address. We use domain names because they are easier to remember than the IP addresses. Another advantage of using domain names when browsing the web is that the IP addresses of servers sometimes change while their domain names usually do not. Having websites such as Google known by their domain names allows the IP addresses to change without confusing the millions of Google users. However, while domain names are much easier for people to remember than IP addresses, routers on the Internet rely on IP addresses to do their work. For this reason, there is a system to keep track of domain names and their IP address. It is called the Domain Name System or DNS. DNS is composed of a group of servers that have a database of the domain names and their corresponding IP addresses. When the IP address of a domain name changes, these servers are automatically updated with the new information. When you type a domain name into the address bar of your web browser and click Go, the name is sent to a DNS server. The server quickly provides your computer with the corresponding IP address. Your computer then sends your website request to the IP address. For your PC to operate properly on a network, one of the required network setup parameters is the IP address of a DNS server. Page 16

17 Network Settings Thursday, November 20, 2008 The next section of the Basic Networking course is Network Settings. Here we will cover the configuration that must be done on PCs or other devices to be able to communicate on any network. Page 17

18 Network Settings Thursday, November 20, 2008 What are the networking parameters that are required when configuring PCs or other devices? The most important one is the IP address of the PC, which we have already discussed. The other required parameters are the IP address of the network gateway, the netmask, and the IP addresses of one or two DNS servers. Page 18

19 Network Settings Thursday, November 20, 2008 We mentioned gateways in the Internet Basics section. Here is a brief review. For a PC on a company network, the gateway is its link to the external network. The gateway IP address is the IP address of the LAN side of the network s router. The PC uses this information when generating messages with a destination that is outside your network. For example, if you attempt to access Google.com, the PC needs to know where to send the request so that it will get to the Internet. The PC sends these requests to the gateway IP address. In this diagram, each PC s gateway IP address will be the LAN IP address of network s router, Page 19

20 Network Settings Thursday, November 20, 2008 Another network configuration setting is the netmask. The netmask, also called subnet mask, is used by the PC to determine if the destination for a message is on your network. The netmask is used to compare the IP address of the message destination with your PC s own IP address. An example is if your company s website is on a server located on the company s own network. If you attempt to access the website, the request should stay on the company s network and not go to the Internet. In this case, the netmask will tell your PC to send the message to the correct server on the company s network. If instead you want to load Google.com, the netmask will indicate to your PC that it should send the message to the company s gateway so it can be forwarded to the Internet. The format of the netmask setting is a special type of IP address. It indicates what parts of the destination IP address must match your PC s address for a destination on the same network. The netmask for many small networks is The 255s indicate that if the first three octets in the destination s IP address match your PC s IP address, the destination must be on your network. If any of the first three octets do not match, the destination must be outside your network. If the destination is outside your network, the PC will send the message to the gateway. Let s look at some examples. Page 20

21 Network Settings Thursday, November 20, 2008 This diagram depicts a network where a PC is on a private network along with a company web server. This network is attached to the Internet through a router. It also shows Google s web server, on the Internet. We will use this diagram to show how the netmask is used to determine where messages should be sent. In this example, the PC has an IP address of , the netmask is , and the gateway is If the user of the PC wants to access the company website, the browser will attempt to send a request to the company's web server. The web server s IP address is Since the netmask has 255 for its first three octets, the PC will examine the first three octets of the destination IP address. In this case, the first three octets of the web server, 192, 168, and 1 match the first three octets of the PC s IP address. Therefore, the request is sent directly to the web server. Page 21

22 Network Settings Thursday, November 20, 2008 Here is another example with a different PC setup. This time, the netmask has been set to This indicates that only the first octet will be compared. The user is trying to access Google s website. The PC must send a request to Google s web server at The PC will first check to see if the Google server is on its own network. It compares the 64 of Google s IP address with 192 of the PC s IP address and finds that they do not match. Instead of trying to send the message directly to the destination, it will send it to the gateway. The gateway will receive the message and forward it to the Internet. The message will work its way across the various networks of the Internet and arrive at Google s web server. Page 22

23 Network Settings Thursday, November 20, 2008 As you have seen, many actions occur when you attempt to connect to a web server through the Internet. To summarize the concepts discussed in this section, let s run through the journey of accessing a website on such a server. This diagram shows a company network with two PCs. Outside the company network, on the Internet, is a DNS server and Google.com s web server. The user of one of the PCs wants to access Google s website. First, type a website address into the address bar of your web browser, such as The browser generates a message for the website requesting its web page. The PC s networking software prepares to send the message but first, it must determine exactly where to send it. The PC sends a request to a DNS server to translate what you typed, into an IP address. The DNS server looks up the IP address and sends it to the PC. The PC determines if the website is on its own network using its netmask. In this case, the IP address is not on the company s network, therefore the PC sends the request to the gateway. The gateway router forwards the message through the Internet. As we saw in the traceroute command, the message gets forwarded through a number of routers, from network to network until it gets to the web server. The web server sends its web page information back to the PC through the Internet. Lastly, your web browser receives the information and displays the website for you to view. Page 23

24 Network Settings Thursday, November 20, 2008 The Dynamic Host Configuration Protocol, also known as DHCP, is a technique used on networks to automatically configure the network settings of devices on the network. Networks usually have a DHCP server that automatically assigns the PC, gateway, netmask, and DNS IP addresses to PCs when they connect to the network. DHCP services can be provided by special-purpose computers or by network routers. The Allworx server can act as a DHCP server if the site does not already have one. If the site already has a DHCP server, the Allworx server can obtain its network settings from that server. Page 24

25 Network Settings Thursday, November 20, 2008 It is possible to place a request to a DHCP server to configure your PC s network settings using a special command called IPCONFIG. IPCONFIG can also be used to view your PC s current network configuration. To run IPCONFIG, you must first open a command window. In the command window, type ipconfig and then press the Enter key. This will display the details of your network configuration. Notice that in this case, the PC has two different network interfaces. The Ethernet adapter Local Area Connection is the interface that we are using to connect to our company s network. It displays the standard network setup information that we ve been discussing. The PC s IP address, subnet mask, and Gateway IP address.. Page 25

26 Network Settings Thursday, November 20, 2008 There are a few options with the IPCONFIG command that you will use frequently when installing Allworx servers. These are the release and renew commands. During the initial setup of the Allworx settings, network communications between the PC you are using and the Allworx server must occasionally be reset. The release and renew options provide the means to perform the reset. Open a command window. Type ipconfig /release and press Enter. You will see that the PC s IP address is reset to all zeros. Then type ipconfig /renew and press the Enter key. This will cause the PC to request network settings from the company s DHCP server. The window will display the new network settings. On some networks, DHCP is not used. The configuration of the settings is done manually by the PC owner or system administrator. Page 26

27 Network Settings Thursday, November 20, 2008 This is the network configuration screen for a PC running Windows XP. The steps for opening the window are different on other operating systems such as Windows Vista. The steps for accessing the network setup screen for both operating systems are provided in the table. Once you arrive at the network configuration screen, you can see that the settings we have discussed: IP address, subnet mask, gateway, and DNS server IP addresses can all be entered manually. If the network has a DHCP server, choose Obtain an IP address automatically. When installing Allworx systems, your PC should almost always be set to obtain automatically. In some cases, an existing customer network may require you to set your IP address manually. Page 27

28 special topics Thursday, November 20, 2008 This section covers a few miscellaneous but important networking concepts. Understanding these concepts will be helpful to you when you set up Allworx systems. Page 28

29 special topics Thursday, November 20, 2008 The first special topic is Media Access Control addresses, otherwise known as MAC addresses. Each network interface on every network device has a unique and permanent MAC address. Because the MAC address is unique and does not change, it can be used to identify the device, much like a serial number. Allworx uses the MAC addresses of its servers and phones as their primary identification. You might think that the IP address could be used for this purpose, however, a device s IP address may change if it is turned off or moved to a different network. The format of a MAC address is six pairs of characters, separated by dashes or colons. Each character in a pair is a base 16 number, otherwise known as a hexadecimal number. This means that each character can be a number between zero and nine or a letter between A and F. Page 29

30 special topics Thursday, November 20, 2008 The term Network Port is sometimes used to refer to the RJ-45 Ethernet jacks on a PC or other network device. However, in this discussion port refers to the software that is the intended recipient of an IP message. When a PC sends a message, the destination information includes the IP address and a Port number. When the message arrives at the destination, the networking software on uses the port number to determine which program should receive the message. For instance, it is possible to log into a server from a remote location using a method called Telnet. When a Telnet login request message is received by the server, the message will specify port 23. This tells the server that the message should go to the server s Telnet software. The Telnet software on the server will receive the login request and send a message back requesting a username and password. Other common network communications use specific ports that are chosen for a single purpose. This includes website contents (on port 80), (which uses port 110), and VoIP phone calls (which use port 5060). Page 30

31 special topics Thursday, November 20, 2008 Firewalls protect networks from malicious hackers that may be operating on the Internet. The term Firewall is borrowed from the construction industry. In buildings, a firewall protects one part of a building from fires in other parts of the building. Nothing can get through a building s firewall except essential wiring and plumbing through carefullyconstructed portals. Similarly, network firewalls stand between the chaos of the Internet and customers networks. Their purpose is to protect the networks from hackers. Hackers are unscrupulous computer experts that would send messages to your network or PC to disrupt their operation, control their operation, or steal personal information. Firewalls prevent these attacks by blocking suspicious or unexpected messages. In addition, using Network Address Translation, they prevent hackers from knowing what PCs are on the protected network and what their IP addresses are. There is enough dangerous activity on the Internet so that every business network, every home network and/or every PC should have a firewall. Firewalls come in two forms, hardware and software. Hardware firewalls are network devices that are connected between the Internet and the company network. Most network routers have a built-in firewall. Software firewalls are programs installed on individual PCs that block suspicious messages as they are received. Another way in which network firewalls are similar to building firewalls is that portals can be opened to allow some messages to pass between the internal and external networks. For instance, if a company has a website that is running on a server on their network, their customers must be able to access the website. In this case, the firewall can be programmed to permit customers on the Internet to access the website without allowing other potentially harmful messages to get through. Page 31

32 special topics Thursday, November 20, 2008 Firewalls selectively permit or reject messages based upon the message port numbers. For instance, a Telnet login from the Internet could be the work of a hacker. For this reason most firewalls are configured to discard messages sent to the Telnet port. However, sometimes Telnet is used by IT departments to perform remote diagnostics. If a site wants to enable this method, the firewall must be configured to permit messages that have a port number of 23, the telnet port. These concepts are important to understand if you are installing an Allworx system behind a site s existing firewall. The firewall will have to be programmed to unblock the ports that are necessary for the Allworx system to function properly. Page 32

33 special topics Thursday, November 20, 2008 Here is the setup screen for the firewall that is built into the Allworx server. The firewall is provided for use at sites that do not already have their own firewall. In the Installation course of the Allworx online training, this screen will be covered in detail. Now, we will go through it briefly to give you an idea of how firewalls are configured. The LAN addresses table is used to permit selected messages to pass through the firewall from the Internet to specific PCs on the LAN. This is done by entering the port number and the intended recipients of the messages using their IP addresses. This setup shows that port 23, the Telnet port, is being permitted to pass through the firewall to a specific PC. Additional ports can be opened for this and other PCs by listing them in the table. The checkboxes at the bottom of the screen allow some common types of messages to pass to all devices on the LAN. These are messages that pertain to common network services. Services such as and VoIP call setup can be selected to pass through the firewall using the checkboxes. The checkboxes are provided as a convenience over entering the ports and IP addresses individually in the section above. Page 33

34 special topics Thursday, November 20, 2008 The next special topic pertains to network switches and hubs. Switches and hubs are junction boxes for connecting PCs and other devices to a network. When setting up an Allworx system, the server and the phones are connected together by plugging all of them into a network switch. Hubs are similar to switches but not suitable for company networks. However, they are useful in certain situations, so we will familiarize you with them. Hubs and switches provide rows of RJ-45 network jacks which are used to connect cables from network devices. Model sizes vary from four or five ports to dozens. Usually, the switch or hub has LEDs on the front panel to indicate the status and activity for each connection. The LEDs flicker when messages are being passed through the port. The difference between hubs and switches is the way messages are routed between the connected devices. Page 34

35 special topics Thursday, November 20, 2008 Hubs connect all of the devices together, like a party line. If a message is being sent through the hub from one PC to another, all devices get the message. However, all but the intended recipient must discard the message. If other devices need to send messages while a message is passing through the hub, they must wait until the first message is done. Therefore, the PCs must take turns. This is an inefficient method that reduces the throughput of communications, and causes delays. Switches prevent these delays, as we will see in a minute. For this reason, switches and not hubs should be used to connect devices to a network. However, hubs can be useful, particularly for troubleshooting network problems. If a site is experiencing problems, a hub can be used to connect a PC to the network to listen in on communications, like on a party line. Using special software tools, the diagnostic PC can log all messages that pass through the hub. This cannot be done using a switch. If logging communications is necessary to diagnose network problems, Allworx Customer Support will instruct you on how to set it up. Page 35

36 special topics Thursday, November 20, 2008 Network switches make more efficient use of the available network capacity. When an attached device attempts to send a message to another device on the network through a switch, the switch sets up a direct connection between the sender and destination. No other devices receive the message. If a second pair of devices needs to communicate, they can do so at the same time. They do not have to wait until the first pair of devices are done. This is more like a switched phone system, unlike hubs which are more like party lines. Therefore, switches are better for company networks. When installing Allworx systems, you will use switches to connect the system components together. Page 36

37 VoIP Thursday, November 20, 2008 Hello and welcome to the Introduction to Voice over IP or VoIP section of the online training. In this section, we will give a brief overview of the technology, benefits, and system settings relating to VoIP telephony and the Allworx system. Page 37

38 VoIP Thursday, November 20, 2008 So what is VoIP? In short, it s a technology that uses computer networking to connect phone calls and transmit audio. Rather than using conventional phone lines, Ethernet networking lines are used. Because of the advantages of VoIP, its use is growing and changing the face of the telephone industry. VoIP is being used in both the consumer and business market. For instance, Skype is a service that both consumers and businesses can use to get low-cost or in some cases free telephone service. By plugging a Skype phone into a PC, you only need an Internet connection to call anywhere in the world. Businesses can use SIP trunks that support multiple VoIP calls over their Internet connection. SIP refers to the network communications protocol that is used to connect VoIP calls. The Allworx system uses Ethernet networks to connect its line of VoIP phones to the Allworx PBX. All internal calls are connected using VoIP protocols. Allworx also uses VoIP to connect sites in a multiple-site installation. For outside lines, Allworx supports the use of SIP trunks, in addition to POTS and T1 lines. Page 38

39 VoIP Thursday, November 20, 2008 So what is this new technology? In VoIP telephony, each phone is a network device. VoIP phones are connected to the company s network through a network switch. Much like a PC, a VoIP phone has an IP address, netmask, and gateway. Allworx phones can use DHCP for automatic configuration, if the network has a DHCP server. A number of communications protocols have been developed for connecting phone calls over networks. The most common and the one used by Allworx is Session Initiation Protocol or SIP. SIP messages are exchanged between VoIP phones, PBXs, and Internet Telephony Service Providers to transmit the phone number being called and the Caller ID of the calling party. If the call is routed over the network to another VoIP phone, that phone uses SIP messages to indicate that it s ringing and that the call is connected, when the party answers,. If the call is eventually routed over conventional phone lines, the VoIP PBX or the SIP trunk provider generates the appropriate signals to the PSTN. When the called party answers, the PBX or SIP trunk converts the answer signals into SIP messages to the caller and the call is connected. The audio that is exchanged between the parties does not use SIP, however. A separate protocol called the Real-time Transport Protocol or RTP is used. The audio from each end is digitized and transmitted in full-duplex across the site s network or across the Internet. Page 39

40 VoIP Thursday, November 20, 2008 There are many benefits of using VoIP in a business environment. The first is that all phone configurations can be done from the PBX. When the phone is plugged into the network, the PBX downloads all of the setup information to the phone. This achieves true Plug-and-Play ease of installation. Another benefit is that VoIP phones can be moved to different locations without changing the phone setup. A user s phone can be moved from one office to another and will be automatically programmed and work exactly as before. If the PBX has access to the Internet, phones can be moved to other locations wherever there is Internet access, such as the employee s home. The only change that must be made is to the network configuration. When in the remote location, calls to the user s extension will continue to ring the phone and if unanswered, they will roll over into the user s voic inbox on the Allworx system. Calls between the phone and other extensions will be toll free and the user can continue to use the company s outside lines. Another important benefit is the ability to integrate multiple sites. If each site is outfitted with an Allworx PBX, calls between the sites will be toll free. Users at either site can call each other using company extensions. Each site can also use the other site s outside lines. This enables calls to be made using the lowest-cost service that is available at any site. Page 40

41 VoIP Thursday, November 20, 2008 Along with the benefits are a few challenges that must be managed. The most important is 911 service. This is particularly problematic for an isolated phone at a remote location. When an emergency call is placed from a remote phone, the call goes through the home site to the 911 call center. In this case, 911 may not be able to route the emergency response correctly. In addition, if Internet service at the remote site is lost, it will not be possible to place any calls, including 911 calls. For this reason, we recommend that every site has at least one POTS line for making 911 calls. Network firewalls can interfere with VoIP telephony if they are not configured to permit the necessary messages to pass. SIP and RTP messages have designated IP ports. These ports must be opened through a firewall at company sites and locations where remote phones are installed in order for VoIP to work properly. The voice quality of phone calls can degrade on congested networks. This can be managed by configuring routers on the site s network to prioritize voice messages over other types of messages. This advanced technique is called managing Quality of Service, or QoS. Finally, Fax does not always work reliably over SIP services. Allworx PBXs support the use of analog Fax machines, but we recommend that the send/receive rate on the Fax machines be set to a slow speed, no faster than 14.4k. Page 41

42 VoIP Thursday, November 20, 2008 In most cases, setting up the VoIP network is simple. For Allworx phones located at the same site as the Allworx PBX, no special configuration is necessary. The phones will get their network settings from the Allworx PBX or the site s existing DHCP server. Once the network connection is set up, the Allworx server will send the phone its settings, software updates, and extension information over the network. If you are using the site's DHCP server, one more step must be performed. The phones must be programmed with the Allworx PBX s IP address. The address can be entered manually into each phone. However, setting it up on each phone can be avoided if the site s existing DHCP server supports something called Option 66. DHCP servers with Option 66 can provide the Allworx PBX s IP address to the phones when it sends the other required network settings. The Allworx PBX IP address must also be programmed into phones at remote sites, such as at an employee s home. In addition, a Secret Key must be entered. This prevents unauthorized users from connecting phones to the company s Allworx PBX. The Secret Key can be found in the Allworx admin screens. It is unique to each PBX. Page 42

43 VoIP Thursday, November 20, 2008 Setting up SIP trunks involves entering account information and choosing some provider-specific options. Application notes with procedures for configuring SIP trunks provided by Allworx SIP Trunk partners are available on the Allworx Reseller Portal. Finally, firewalls between phones, the PBX, and SIP trunk providers must be configured to unblock the SIP and RTP ports. This includes firewalls at customer sites and remote phone locations, such as an employee s home firewall. Page 43