Internet GW Telephony Richard Cox AT&T Labs - Research
An Internet Phone Call
Internet Phone Call Appearance Incoming Phone Call From: Larry Rabiner Subject: Internet Telephony Report Options Selected by Caller: 7 khz Audio Whiteboard for sharing documents How do you wish to respond? Answer the call Forward to Voicemail
Phone Call Appearance Internet Telephony: New Service Offerings Incoming Phone Call R. V. Cox From: Larry Rabiner AT&T Labs-Research Subject: Internet Telephony Report Options Selected by Caller: June 7, 72000 khz Audio Whiteboard for sharing documents How do you wish to respond? Answer the call Forward to Voicemail -1-
Phone Call Appearance Internet Telephony: New Service Offerings Incoming Phone Call R. V. Cox From: Larry Rabiner From: Nancy Cox AT&T Labs-Research Subject: Internet Telephony Report Subject: Dinner Plans Options Selected by Caller: Options Selected by Caller: June 6, 72000 khz Audio 7 khz Audio Whiteboard for sharing documents How do you wish to respond?: How do you wish to respond? Answer this call (1st call on hold) Answer the call Conference both calls Forward to Voicemail Forward to Voicemail Open text chat to caller -1- Incoming Phone Call
Text Chat Window Rich> I can t talk now. I m on the phone with Larry. Do you want to go out to dinner tonight? Nancy> How about Chinese? Rich> OK What time? Nancy> How about 7? Rich> OK
Phone Call Appearance Internet Telephony: New Service Offerings Incoming Phone Call R. V. Cox From: Larry Rabiner AT&T Labs-Research Subject: Internet Telephony Report Options Selected by Caller: June 7, 72000 khz Audio Whiteboard for sharing documents How do you wish to respond? Answer the call Forward to Voicemail -1-
Phone Call Appearance Internet Telephony: New Service Offerings Incoming Phone Call R. V. Cox Outbound Phone Call From: Larry Rabiner AT&T Labs-Research Subject: To: Chuck Internet Kalmanek Telephony Report Subject: Conference call Options Selected by Caller: with Larry now June 6, 72000 khz Audio Whiteboard Out of office for - sharing forwarding documents call How Reached do you wish at cell to phone respond? Answer Conferencing the call notebook PC Forward to Voicemail -1-
Fact or Fiction? Could this call happen today? Next year? Ever? Soon the protocols are almost completed hardware and software are right behind them getting everyone networked will take the longest time IP Telephony Usage Minutes (Billions) 700 600 500 400 300 200 100 0 98 99 00 01 02 03 04 05 YEAR Usage Market forecast from Voice over Packet Market Forecast, Probe Research, Inc., 1999
Definitions POTS - Plain Old Telephone Service PSTN - Public Switched Telephone Network, what POTS runs on Voice over Internet Protocol (VoIP) - transmission of voice for telephony or other applications using IP Internet Telephony - duplicating and enhancing the functionality and capabilities of conventional telephony using VoIP for at least some portion of the connection for the immediate future, Internet Telephony will co-exist and must interwork with the PSTN
Outline Introduction History & Motivation Current status of Internet Telephony Future of Internet Telephony
In the beginning (~1995) Create PC to PC voice over an Internet connection Phone charges too high between US and Israel Call it an Internet Phone Sell software to make free phone calls
Motivations for Internet Telephony Avoiding tariffs and fees associated with PSTN the first Internet Phone sought to avoid international settlement charges in the US Internet Phone service avoids access fees paid to the local phone companies to complete long distance calls Achieving greater economies of scale by merging with the Internet/data/packet network data network traffic will dominate voice traffic in the 21st century, thus data network equipment should be less expensive than PSTN equipment CPE communications costs for equipment and service can be combined in a common system New services relying on multimedia communications IP provides the glue to prototype & deploy innovative, new services quickly and at low cost
Why Internet Telephony? For a consumer Reduced costs, e.g. New services bundled with IP, e.g. Click2Dial For a business/enterprise customer Convenient, single multi-service interface Dynamic bandwidth allocation between voice & data Future-Proof Evolution For a carrier Convergence to one network Economies of scale in building and operations New services built on new applications
Types of Calls Consumer Long Distance Business Long Distance 800 Number Software Defined Network Consumer Local Calls Business Local Calls Other Voice Traffic Components of Cost for a Call Network Other Operations Access In selecting Internet Telephony as a replacement for PSTN in a market segment, which costs are being reduced or increased? Note: relative portions of cost and percentage of traffic types is proprietary
Taking a closer look: telephony ~1900 VOICE VOICE operator Switching: operator placed call for customer, making both the physical connection and knowing the database of subscribers Alerting: the ringing tone alerts the customer of an incoming call Voice Quality: limited by physical laws, awaiting invention of a practical amplifier to enable truly long distance telephony Networking: local monopolies or multiple companies without interconnection Security: not even on the horizon Billing: local service is all you can eat, long distance is metered
Taking a closer look: Internet Telephony ~1995 Voice Internet Voice Switching: replaced by best effort routers along the connection; caller must include destination in IP packet header Alerting: callers must pre-arrange calls to be near their computers; can create an alerting signal Voice Quality: limited by latencies of sound cards & routers, packet loss, bandwidth of modems, & computational capability of PCs, in a word -- TERRIBLE Networking: Internet backbone is free, but best effort; access is via ISP Security: encryption could provide great security; denial of service a threat Billing: calls are free, but both parties must pay for Internet connection & PC
Internet Telephony Challenges Setting up a call Interworking with the PSTN interoperation with SS7 for messaging gateways between PSTN and IP networks Improving the quality of service (QOS) reducing one-way delay to < 150 ms reducing jitter (main cause of lost packets) keeping lost packets to a minimum (~1%) Security aspects encryption: privacy vs government wiretaps theft of service: authentication, spoofing denial of service
Call Setup and Completion Traditional Circuit Switched Network Signaling for Call Setup and Control over SS7) Voice Circuit (Dedicated Resources for duration of call) Off hook -> switch initiates dial tone to customer Dial number -> Network knows when you ve dialed the correct number of digits Network does database dip to map number to physical address Ringing initiated on called party phone caller ID (ANI) included in signal to called phone caller waiting function alerts called party if phone is in use Call Completion called party answers phone -> make physical connection busy signal generated no answer, ringing continues
Outline Introduction History & Motivation Current Status of Internet Telephony standards current services Future of Internet Telephony
Standards Bodies ITU-T Study Group 16 H.323 and associated standards Internet Engineering Task Force (IETF) Session Initiation Protocol (SIP) Media Gateway Control Protocol (MEGACO) European Telecommunications Standards Institute (ETSI) TIPHON project (Telephone-IP Harmonization of Networks) International Multimedia Teleconferencing Consortium (IMTC) INOW (Interoperability Now) ahit (applications harmonization for Internet Telephony)
Standards Challenges Call setup and administration H.323, SIP, MGCP Interworking with other protocols inow, SIP-H.323 IWF, ahit, gateways to PSTN Quality of Service delays caused by best effort networks extra delay destroys conversation dynamics variable delay leads to packet loss
H.323 (ITU-T) Standards Teleconferencing control protocol extended to IP Telephony infrastructure inow interworking profile developed Main limitation is complexity of implementation MGCP (IETF) Media Gateway Control Protocol that separates signaling gateway from media gateway Effective for transparent VoIP or VoATM service SIP (IETF) Session Initiation Protocol designed for real-time Multimedia IP applications Designed for both transparent and enhanced IP applications with links to web pages, email, etc.
RSVP, RTP, Diffserv & MPLS RSVP is the Resource Reservation Protocol which permits bandwidth to be reserved this is a single message to initiate the reservation RTP is an IPv6 protocol designed to provide end-to-end network transport functions for applications transmitting real-time signals such as voice RTP provides services such as payload type ID, sequence numbering, time stamping, and delivery monitoring DiffServ defines the existing Type of Service bits in the IP header so the network knows how to prioritize traffic major vendors plan to implement DiffServ this year MPLS provides a mechanism to group multiple packets into a single flow group, something akin to ATM virtual circuits, for flow through broader bandwidth connections MPLS exchanges data link layer labels for networking layer labels
Resolving the QOS Challenge IETF is taking the lead on protocols to improve QOS RSVP, RTP, Diffserv, MPLS old idea of best effort, one class of service is eliminated bits already exist for this in IPv4 and more in IPv6 need to be implemented by router vendors ITU-T can help by making media coders that are more tolerant of packet losses G.711 PLC is a major example More experience with network engineering is needed to identify problems and discover good practices These 3 approaches complement each other and will resolve the problems to meet the QOS challenge
Taxonomy of Internet Telephony Applications Phone to Phone consumer cost savings, calls originate and terminate on PSTN e.g. AT&T Connect n Save, Sprint Callternatives PC to Phone greater consumer costs savings, new services, one end of call is not a PSTN phone, e.g. Net2Phone free calls PC to PC greatest possibility for innovative, new services
Today s Internet Telephony Example 1 - Discount Phone Calls a variety of companies offer deep discounts on PC-to-phone and phone-to-phone IP calls e.g., AT&T, deltathree.com, Deutsche Telekom, Glocalnet AB, Ipirion, KDD, Net2Phone, dialpad, Singapore Telecom, Sprint, STAR Telecom, Telia also discount FAX via the Internet e.g., JFAX, KDD, Net2Phone, Singapore Telecom
Today s Internet Telephony Example 2 - Voice Chat Yahoo, Excite, and AOL all offer online Voice Chat services chat with people on your buddy list chat with others in a chat room make conference calls with a group Initial service was push-to-talk new service is pseudo full-duplex
Today s Internet Telephony Example 3 - E-commerce you want more info than there is on the web page, just Click to Talk to a live agent Internet phone call is established between your PC and the agent you ask the agent your questions agent answers verbally agent can push additional web pages to you
Today s Internet Telphony AT&T Virtual Communication Services SM WISL - Virtual Call Center
Outline Introduction History & Motivation Current status of Internet Telephony Future of Internet Telephony
Market forecast from Voice over Packet Market Forecast, Probe Research, Inc., 1999 Projections on IP Telephony Gateway Sales Millionns US Dollars ($) 40 35 30 25 20 15 10 5 0 800 700 600 500 400 300 200 100 0 Gateway Port Sales Projections 98 99 00 01 02 03 04 05 YEAR Price Per Port 98 99 00 01 02 03 04 05 YEAR Ports Price Port projections may not include 3G wireless which should begin entering the market in 02-03 Price drops as industry moves away from PCbased gateways to greater density systems Software component of price per port expected to increase from $40 in 00 to $51 in 05
Internet Telephony Usage Internet Telephony Minutes Billions 800 600 400 200 0 98 99 00 01 02 03 04 05 YEAR Low Medium High Current Market Drivers current discounts E-commerce voice chat Future Market Drivers 3G Wireless (all IP) Packet Cable Telephony DSL-based solutions Market forecast from Voice over Packet Market Forecast, Probe Research, Inc., 1999
The IP Phone of the Future IP is the common denominator Access: DSL, cable modem, fiber optics, 3G wireless Session Initiation Protocol (SIP) flexible, lightweight, easy to provision new services greater call control for users Session Description Protocol (SDP) capability descriptions exchanged at setup Real-time Transport Protocol (RTP)
IP Phone Terminals How may I help you? Multimedia PCs - full functionality, handsfree speakerphone or handsets desktops or notebooks Digital TV & Set top box full functionality just like PC 3G wireless phone with small visual display PDA - better visual display, poorer audio POTS phone limited functionality but IP network will still interconnect with PSTN
User Interfaces POTS user interface is well known, highly limited in its functionality, and indistinguishable among service providers IP user interface can be customized for each individual network stores each user s preferences, address book, etc. user interface can retain the same look and feel across different devices
Summary Why Internet Telephony Will Prevail Current discount phone call plans take advantage of regulatory anomalies companies in this space can plow back profits to build larger networks, while eroding profits of traditional phone companies Long term economics favor data network equipment over circuit switched networks economies of scale force the usage of IP IP Telephony will offer more innovative new services than traditional telephony it s a simpler space to work in more applications creators in IP space Current QOS problems will be overcome by better network engineering, new QOS protocols, and signal processing