An ADTRAN White Paper. Integrating LAN Fax Servers over T1 and PRI Services

Transcription

1 An ADTRAN White Paper Integrating LAN Fax Servers over T1 and PRI Services

2 Migration to LAN Fax Servers Introduction While many may argue that the universal acceptance of electronic mail has all but replaced facsimiles (fax), fax technology is still considered a vital part of business-to-business communication. However, in this new age of e-document delivery, more and more companies are moving from manual faxing to network-based fax server solutions. This migration involves the transition from traditional departmental walk-up fax machines to an enterprise wide network fax server solution; in most cases, leveraging existing IT hardware and software to provide e-document delivery from virtually any desktop, or serverbased back office application. Integrating fax into the existing infrastructure makes it much easier for end users to send and receive faxes, since faxing just becomes a natural extension of . Just Give Me the FAX One of the most important features of network faxing is the ability to automatically route incoming faxes to any recipient within the organization. This process alleviates the manual review and routing of faxes, while ensuring the timely delivery and confidentiality of fax transmissions. As with routing voice calls, the ability to route fax calls to a particular fax mailbox is accomplished through the use of Direct Inward Dial (DID) or Dialed Number Identification Services (DNIS) from the telephone service provider. DID/DNIS service provides each user with his/her own unique telephone number, which is used by the fax server to designate and route calls to a specific fax mailbox. Most of the network fax servers sold today have the ability to route faxes based on the DID/DNIS digits through the use of T1, Primary Rate ISDN (PRI), and/or analog interfaces. While the flexibility and feature support of a T1/PRI is much greater than that of traditional analog DID trunks and Plain Old Telephone Service (POTS), most companies cannot afford, nor do they require the full channel density of T1/PRI for faxing only. In fact, most of today s smalland medium-sized businesses only require eight or fewer lines for faxing based on the average simultaneous inbound and outbound fax traffic. This is why many companies choose the analog interface option based on lower initial equipment cost and limited port requirements. Unfortunately, many customers have discovered after the purchase of their analog fax server that the process of ordering telephone services to match the requirements and feature sets of their servers is confusing and frustrating. The purpose of this paper is to provide information to help you make an informed decision when selecting telephone services and fax server interfaces to meet your fax requirements. This paper will also outline solutions for using T1 and PRI services as a way to consolidate both fax and voice services, and discuss the process of ordering and provisioning these services to maximize the full capabilities of the fax server. 2 Integrating LAN Fax Servers over T1 and PRI Services

3 Let s Talk Analog for a Minute Most of the fax servers and fax boards available today have options for supporting three basic types of analog interfaces: DID, loop-start/pots, and E&M. While the feature support for each of these interfaces may vary between manufacturers, the analog features provided by the network service provider and PBX manufacturers will remain somewhat consistent. Below is a breakdown of the typical analog services available and features provided with each option. 1. Analog (DID) Trunks: DID trunks are 2-wire circuits provisioned with E&M Wink or immediate signaling, delivering DID/DNIS digits for call routing. The downside to analog DID service is that it only supports inbound calling. Outbound calling is not supported. 2. Analog (POTS) Trunks: These trunks are 2-wire circuits provisioned for either loop-start or ground-start signaling. While most loop-start and ground-start lines delivered from the service provider are two-way, they do not provide DID/Dual Tone Multi-Frequency (DTMF) digits for incoming calls, meaning only ring current is passed to the customer premise. 3. Analog E&M Trunks: These trunks can be provisioned as 2-wire or 4-wire interfaces (+ E&M leads), with the ability to pass DNIS/DTMF digits for both inbound and outbound calls. Unfortunately, since most PBX systems and telephone service providers no longer offer analog E&M service, it is difficult to find fax board manufacturers that still produce and/or support analog E&M interface cards. I Want My DID Despite the feature support offered by the service provider, many fax server/board manufactures have engineered their Analog (POTS) Interfaces to support inbound call routing based on DID/DNIS digits. This is often a point of confusion in the telephony world. As stated earlier, analog POTS service delivered from a PBX or network service provider does not provide DID/DNIS digits. This poses the question, why would fax server manufactures embed support for a feature that is not available from the network service provider or supported in a PBX system? This is because most T1 Multiplexers and Integrated Access Devices (IADs) have the ability to pass DTMF/DNIS over standard POTS interfaces when terminating T1 or PRI service from the network service provider. So What are the Advantages of Using T1 or PRI Service? T1 and PRI services provide several important benefits, including flexibility, channel density, and expanded routing capabilities. When equipping the fax server with a T1 or PRI interface card, the provisioning and equipment selection process is generally easy and painless to implement, since the only requirement is to match the T1/PRI circuit provisioning with the configuration of the fax server interface. But as stated earlier, using a T1 or PRI circuit for faxing only is generally cost prohibitive and typically overkill for most small-to-medium sized businesses. On the other hand, it is common for most small-tomedium sized businesses to have one or more existing T1 or PRI circuits delivering voice and/or data services that could also be used to transport fax traffic with the addition of an IAD. An ADTRAN White Paper 3

4 The PBX Theory Since most customers already have existing T1/PRI connections to their PBX, a common approach is to use analog extensions off the PBX to connect the fax server. While few would argue that this is probably the easiest and most cost-effective approach, the downside is that most analog station ports do not pass DNIS/DTMF from the PBX. Just like a POTS line delivered from the network service provider, analog extensions on most PBX systems do not have the ability to pass DID/DTMF, only ring current is passed. This means the customer is forced to sacrifice call routing to particular fax mailboxes through the use of DID/DTMF digits. No DNIS/DTMP Digits are passed, the fax server only receives RING A second option for connecting a fax server to a PBX system is using analog E&M trunks between the two devices. But as mentioned earlier, while it is true that analog E&M trunk ports on a PBX will pass bi-directional DNIS/DTMF, most of the newer PBX systems and fax servers no longer offer an analog E&M option. Network Service Provider T1/PRI PBX DNIS/DTMP Digits of 8001 Passed Analog E&M Trunk Ports Fax Server Figure 2 PBX system delivering analog E&M Trunk ports to an attached fax server. Network Service Provider PBX Analog Station Ports Fax Server Figure 1 PBX system delivering analog station ports without DNIS/DTMF to an attached fax server. 4 Integrating LAN Fax Servers over T1 and PRI Services

5 CRAF T POWER SYSTEM ETHERNET REMOTE ACO OK ERROR ALARM NETWORK 1 2 STATUS ONLINE MODULES ATLAS 550 CRAF T POWER SYSTEM ETHERNET ACO REMOTE NETWORK OK ERROR ALARM 1 2 STATUS ONLINE MODULES ATLAS 550 The IAD Solution IAD to the Rescue To this point we have focused primarily on the issues and problems associated with integrating analog fax servers in the enterprise network; however, we now shift our attention to discussing solutions using IADs. An IAD is classified as a compact platform that installs quickly at the customer premises and provides multiple interfaces for connecting other equipment at that location. As a common feature set, most IADs support both analog and digital interfaces, enabling customers to share a single T1 or PRI circuit between multiple devices equipped with similar or disparate interfaces. Most IADs on the market today support a variety of interfaces including Foreign Exchange Office (FXO), Foreign Exchange Station (FXS), T1, PRI, as well as various serial interfaces for video and data communications. Network Service Provider T1/PRI Integrated Access Device T1/PRI Figure 3 Typical IAD application, sharing a single T1/PRI circuit between multiple CPE devices. The Static IAD Solution PBX FXS Fax Server While most IADs provide similar functionality, the feature support of these devices can vary greatly. Basically, there are two types of IADs on the market today. The most basic provides static or dedicated timeslot mapping of the network T1 DS0s, while the intelligent IAD supports dynamic timeslot utilization for call-by-call routing. The static IAD solution is often referred to as a MUX or channel bank, supporting timeslot/channel mapping from the network T1 to a particular interface connecting the CPE. This is generally referred to as a static device, since the timeslots mapped from the network T1 to a particular interface cannot be used by other interfaces in the chassis. As an example, assume a customer wants to share a single T1 between a fax server equipped with a 4-port analog interface and a PBX equipped with a T1 card. If channels one through four on the network T1 are mapped to analog FXS ports connecting a fax server, and the remaining channels (5-24) are mapped to a DSX-1 interface connecting a PBX, the PBX has no way of utilizing the four channels reserved/mapped to the fax server, or vice versa. In the event that all channels connecting the fax server are sitting idle, while all 20 channels mapped to the PBX are busy, the PBX has no way of utilizing the four idle channels mapped to the fax server. This less efficient use of bandwidth generally results in a customer subscribing to more bandwidth than would have been required with a dynamic IAD solution. In addition, the static timeslot assignment requires the service provider to provision multiple trunk groups on the T1, which can further complicate the implementation process, and in many cases increase monthly service provider fees. Network Service Provider Trunk Group #1 T1 Channels 1 20 Number Range (256) Trunk Group #2 T1 Channels Number Range (256) T1 Integrated Access Device Number range of that is statically assigned to T1 channels 1 20 are mapped to a DSX-1 interfaces connecting the the PBX. Figure 4 T1 Mux/channel bank (static solution) terminating a single T1 circuit provisioned with multiple trunk groups. T1 FXS PBX Fax Server Number range of that is statically assigned to T1 channels are mapped to FXS interfaces connecting the fax server. An ADTRAN White Paper 5

6 CRAF T POWER SYSTEM ETHERNET REMOTE ACO OK ERROR ALARM NETWORK 1 2 STATUS ONLINE MODULES ATLAS 550 Number range of (256) provisioned as a single trunk group and assigned to all channels of the T1/PRI from TELCO. Network Service Provider The Dynamic IAD Solution For some customers, the static solution may work fine; however, others may desire a more dynamic switching solution that provides full utilization of their T1 or PRI bandwidth. This dynamic approach is accomplished through the use of circuit switching and call-by-call routing. This allows T1 and PRI channels to be shared between multiple applications, eliminating the need to dedicate bandwidth for each end user device. Unlike the static solution, the network service provider is not required to configure multiple trunk groups since dynamic call routing between interfaces is performed in the dial plan of the IAD. In addition, hunt group and distribution group configurations generally performed by the network service provider are performed by the IAD, allowing the end-user customer to have full control over call routing assignments, further simplifying the circuit provisioning process. Furthermore, this dynamic solution adds support for PRI service, which provides more efficient call routing and expanded feature support, at a fraction of the cost of standard T1/Robbed Bit Signaling (RBS) service in some areas of the country. In figure 5, the IAD is terminating a single PRI from the network service provider and dynamically switching calls to an attached fax server and PBX. The IAD is converting PRI on the network side to analog FXS ports configured to pass DTMF to an attached fax server, while also simultaneously routing calls to an attached PBX via T1 or PRI interface. T1/PRI Integrated Access Device Number range of dynamically routed to the PBX. T1/PRI PBX FXS Fax Server FXS and FXO Defined Regardless of which IAD solution you choose, it is important that you know the interface requirements of the fax server before selecting the IAD. Unlike the analog POTS applications described in Figures 1-5, some fax vendors choose to manufacture only analog DID interfaces for inbound call routing with DNIS. As mentioned earlier, an analog DID interface supports incoming calls only, therefore, outbound dialing must be performed over a different interface. In most cases, these vendors offer an analog loopstart/pots option for outbound dialing, but do not embed support for inbound call routing through the use of DNIS/DTMF. In cases where inbound call routing with DNIS and outbound faxing is required, the manufacturer will offer a combination card that is equipped with both DID and analog POTS interfaces on a single module. The DID ports are utilized for inbound calls and the analog POTS for outbound faxing. Regardless of which type interface you choose in the fax server, it is important that you match the electrical characteristics with the module selection in the IAD. When using incoming only DID interfaces in a FAX server, the FXO module is used in the IAD. When using loop start (POTS) interfaces in the fax server, an FXS module is required in the IAD. The primary difference between the two IAD modules is that the FXS provides 48V battery, while the FXO module is looking for battery from the attached CPE interface. If you are having a hard time determining the right module selection for your IAD, simply ask the fax server manufacturer if the interface card is providing battery or looking for battery. If the fax server interface is looking for battery, then an FXS module is required in the IAD. Likewise, if the fax server interface is providing battery, the FXO module is required. (See Figures 6 and 7 for more details.) Number range of dynamically routed to the fax server. Figure 5 This intelligent IAD dynamically switches calls between multiple interfaces based on digits dialed. 6 Integrating LAN Fax Servers over T1 and PRI Services

7 CRAF T CRAF T POWER SYSTEM ETHERNET REMOTE POWER SYSTEM ETHERNET REMOTE NETWORK 1 2 OK ERROR ALARM NETWORK 1 2 OK ERROR ALARM STATUS ONLINE STATUS ONLINE MODULES MODULES ATLAS 550 ATLAS 550 Integrated Access Device -48V or battery generated by the FXS card Server Analog Loop-Start ACOFax FXS Interface (POTS) Interface Fax server (POTS) interface looking for battery generated by the IAD Figure 6 Common FXS Application Connecting a Fax Server with POTS Interface Integrated Access Device IAD FXO interface looking for battery generated by fax server Server Analog DID Interface ACOFax FXO Interface (Incoming Only) V or battery generated by the fax server interface Figure 7 Common FXO Application Connecting a Fax Server with DID Interface An ADTRAN White Paper 7

8 Ordering T1 and PRI Service T1 and PRI Provisioning To this point we have discussed the fax server interface selection and how to match the capabilities and feature support of the fax server to the appropriate IAD. However, the final step in this process is to properly provision the T1 or PRI service delivered from the service provider to match the requirements and feature support of both the fax server and the IAD. When provisioning a standard T1 RBS circuit, it is important to understand that T1 RBS has basically four signaling options. While we could overwhelm you with the bit level detail of how each of these signaling methods differ, it is more important to understand the feature support of each service to ensure proper provisioning based on the requirements of your application. E&M Wink or Immediate: E&M Wink/Immediate is the only RBS signaling option that provides DID/DNIS digits for call routing. When the fax or voice telephony application requires the flexibility of bi-directional (e.g. inbound and outbound) call routing, E&M Wink or Immediate signaling is the correct signaling option to use. When provisioning E&M service, your provider will also need to know the number of DNIS digits required. It is important that you discuss this with your fax server and/or PBX vendor before making this decision, since this number depends upon the number of digits the fax server or PBX is expecting to receive. (i.e. If the fax server is configured using four-digit fax mailbox numbers, then it is likely the circuit should be provisioned to only pass the last four DNIS digits.) Loop Start or Ground Start: As with analog (POTS) service, the network service provider does not provide DNIS/DTMF digits when a T1 is provisioned for loop-start or ground-start signaling. While limited, this may be an appropriate signaling option to choose for outbound-only faxing, or when the application does not require routing of incoming calls through the use of DID/DNIS digits. An alternative to standard T1/RBS service is ISDN PRI. Unlike T1/RBS signaling that takes place on each of the individual 24-channels of the circuit, PRI utilizes a single channel to provide signaling for the remaining 23 bearer channels on the T1. Like T1/RBS provisioned with E&M signaling, PRI has the ability to pass DID/DNIS digits to the CPE. However, due to the single signaling channel design of PRI, the circuit cannot be muxed or statically mapped like T1/RBS. Therefore, a dynamic IAD solution is required. The primary concern when provisioning PRI service is to ensure the ISDN switch type used by the carrier is supported by the IAD, (e.g. National ISDN 2, Lucent 5ESS, DMS-100). Beyond switch type verification, most of the other provisioning and configuration requirements are performed in the IAD. 8 Integrating LAN Fax Servers over T1 and PRI Services

9 Summary As with any implementation, the key to successfully integrating a LAN fax server over new or existing T1/PRI service is good communication between all parties involved: the network service provider, fax vendor, IAD vendor, PBX vendor, etc. This process, along with a good understanding of the telephony services and how to match these services with the feature support and requirements of the fax server are key components to ensuring a smooth fax server implementation. An ADTRAN White Paper 9

10 ADTRAN, Inc. Attn: Enterprise Networks 901 Explorer Boulevard Huntsville, AL P.O. Box Huntsville, AL voice fax General Information 800 9ADTRAN Pre-Sales Technical Support toll-free Where to Buy toll-free About ADTRAN ADTRAN, Inc. is one of the world s most successful network access equipment suppliers, with a 17-year history of profitability and a portfolio of more than 1,300 solutions for use in the last mile of today s telecommunications networks. Widely deployed by carriers and enterprises, ADTRAN solutions enable voice, data, video, and Internet communications across copper, fiber, and wireless network infrastructures. ADTRAN solutions are currently in use by every major domestic service provider and many international ones, as well as by thousands of public, private and governmental organizations worldwide. Post-Sales Technical Support support@adtran.com ACES Installation & Maintenance Service ACES aces@adtran.com International Inquiries voice fax international@adtran.com For the regional office nearest you, visit: ADTRAN is an ISO 9001, ISO and a TL 9000 certified supplier. ADTRAN, Inc. 901 Explorer Boulevard Huntsville, Alabama P.O. Box Huntsville, Alabama ADTRAN voice fax info@adtran.com web site ADTRAN, Inc. is an Equal Opportunity Employer committed to utilizing Minority Business Enterprises (MBE), Woman-Owned Business Enterprises (WBE) and Disabled Veteran Business Enterprises (DVBE) whenever possible and practical for procurements supporting ADTRAN and our customers. Copyright 2005 ADTRAN, Inc. All rights reserved. ADTRAN is a registered trademark of ADTRAN, Inc. All other trademarks and registered trademarks are the property of their respective owners. EN700A