Kundan Singh and Henning Schulzrinne Columbia University Agenda

Kundan Singh and Henning Schulzrinne, Columbia University Agenda • Introduction • Requirements • Architecture • Issues • Implementation • Q/A

Traditional voice mail system Dial 853 -8119 Alice 939 -7063 Phone is ringing. . The person is not available now please leave a message. . . Your voice message. . . Disconnect Bob can listen to his voice mails by dialing some number. Bob 853 -8119

Problems • Voice mail system tied to PBX or phone company (if CFB) • Integration of video, fax, whiteboard? • How to integrate with Internet telephony? • How to integrate with email, web and other user applications?

Existing solutions • Voice Profile for Internet Messaging (VPIM) • Web-based unified messaging systems with personalized PSTN voice mail number.

Design Goals • • • Message recording and playback Universal access: web, email, Vo. IP, PSTN Email notification Scalability for large domains Separable from ITSP or ISP Reuse existing infrastructure Media-agnostic Tool-agnostic Telephony interface - DTMF

Why SIP and RTSP ? • Use SIP for accepting voice/video calls (other services, and infrastructure for Internet telephony) • RTSP for storage and access of voice messages. • RTSP already in common use, e. g. , Real. Player • Large-scale RTSP Mo. D servers exist. • Easy integration with web, email, video and fax. • Access from PSTN using a gateway.

Architecture Bob INVITE bob@phone 1. office. com INVITE bob@office. com REGISTER bob@vm. office. com Alice INVITE bob@vm. office. com The voice mail server registers with the SIP proxy, sipd, on behalf of every user. Alice calls bob@office. com through SIP proxy forks the request to Bob’s phone as well as to a voicemail server.

Architecture Bob phone 1. office. com; CANCEL 200 OK Alice 200 OK RTP/RTCP After 10 seconds vm contacts the RTSP server for recording. vm accepts the call. Sipd cancels the other branch and. . . accepts the call from Alice. Now user message gets recorded v-mail vm. office. com; SETUP rtspd

Architecture Bob phone 1. office. com Email to bob@office. com BYE Alice 200 OK RTP v-mail vm. office. com Once the call is closed by Alice, vm sends an email to Bob informing him of the arrival of a voice mail.

Architecture Bob phone 1. office. com INVITE bob-526156 -retrieve@vm. office. com Alice RTP Quick-time v-mail vm. office. com Bob can listen to voice mail using either an RTSP client like Quick. Time or. . . by calling the v-mail using SIP. …or by visiting his web-based voicemail account SETUP/PLAY rtspd RTSP

Architecture Alternatives – The SIP phone redirects the call to voice mail after 10 seconds. – The SIP proxy is configured to forward the call to voice mail if your phone is busy or there is no response (static, or using sip-cgi, CPL) – Voice mail server acts as another phone for the user but delays accepting the call by 10 seconds, with CANCEL if user picks up.

Issues • • Call reclaiming Deleting voice/video mail Integration with PSTN phone Integration with VPIM, IMAP, POP 3

Implementation • Prototype system. • Recording and playback using. au files. http: //www. cs. columbia. edu/vmail

Implementation Features • Integration with web/email for more control over voicemail configuration (e. g. , folder management, email notification. ) • Web based voice mail accounts for users (Similar to Hotmail) • Retrieval using RTSP clients (Quicktime), SIP user agent (e*phone) or Web browser.

Implementation Future • • DTMF based navigation Support for other media formats in rtspd Deployment Multimedia mail SIP retrieval

Conclusion • SIP and RTSP - good framework for unified messaging • Integration of voice/video mail/answering machine, email, instant messaging, fax, etc.

Conclusion Wide range of applicability Campus/corporate network Internet rtspd sipum rtspd Within a domain External application service provider