1. IRT Lab IP Telephony Deployment @ Columbia 1 Henning Schulzrinne Wenyu Jiang Sankaran Narayanan Xiaotao Wu Columbia University Department of Computer Science {hgs,wenyu,sankaran,xiaotaow}@cs.columbia.edu

2. IRT Lab IP Telephony Deployment @ Columbia 2 IP Telephony and Protocols External line 7040 7042 PBX Corporate/Campus Internet LAN 8154 8151 8152 8153 PBX Another campus LAN IP Phone Client/ Audio over RTP VoIP Gateway home.com office.com SIP server SIP server Call “bob@office.com”

3. IRT Lab IP Telephony Deployment @ Columbia 3 Architecture SIP proxy, redirect server SQL database sipd SIPH.323 convertor NetMeeting sip323 H.323 rtspd SIP/RTSP Unified messaging RTSP media server sipum Quicktime RTSP clients RTSP SIP conference server sipconf T1/E1 RTP/SIP Telephone Cisco 2600 gateway Telephone switch Web based configuration Web server Cisco 7960 3Com e*phone sipc Software SIP user agents Hardware Internet (SIP) phones Pingtel SNMP

4. IRT Lab IP Telephony Deployment @ Columbia 4 CINEMA: Columbia InterNet Extensible Multimedia Architecture Web interface –Administration –User configuration Unified Messaging –Notify by email –rtsp or http Portal Mode –3 rd party IpTelSP

5. IRT Lab IP Telephony Deployment @ Columbia 5 PSTN-IP Inter-Operation PBX PSTN External T1/CAS Regular phone (internal) Call 9397134 1 SIP server sipd Ethernet 3 SQL database 4 7134 => bob sipc 5 Bob’s phone Outgoing calls are similar Gateway Internal T1/CAS (Ext:7130-7139) Call 7134 2 5551212

6. IRT Lab IP Telephony Deployment @ Columbia 6 sipc – A SIP User Agent

7. IRT Lab IP Telephony Deployment @ Columbia 7 Controller SIP Stack Transmission Controller SIP Stack Transmission Service Logic Execution Environment CPL script CGI script Service Creation Environment Service Logic Execution Environment CPL script CGI script Service Creation Environment GUI Media transmission Media application Media application sipc Architecture

8. IRT Lab IP Telephony Deployment @ Columbia 8 What about Audio Quality? Voice Codec: G.711 = toll quality at 64 kb/s Bandwidth: rarely an issue on campus networks with Gigabit core switches Measurement in the Columbia intranet (campus- wide), over a total of 24 hours –Average (one-way) delay < 1ms –Jitter: packets > 10ms = 0.003%-0.05% –Loss: 0.001%-0.01%, 0.005% average Using Ethernet switches instead of hubs prevents excessive delay/jitter.

9. IRT Lab IP Telephony Deployment @ Columbia 9 Scalability, Security and Other Scalability based on multiple servers: –SIP Server, via DNS SRV –Gateway and LAN bandwidth –Media servers (voice-mail and conferencing) Security: –Authenticate users; Disallow auth-bypass. –Gateway calls for only authorized users. Further issues of study: –Service availability/reliability, QoS –Privacy/encryption, Electronic Billing