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Unified Messaging using SIP and RTSP. Kundan Singh and Henning Schulzrinne, Columbia University. Agenda Introduction Requirements Architecture Issues Implementation Q/A. Dial 853-8119. Phone is ringing. Disconnect. Alice 939-7063. Bob 853-8119.
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Unified Messaging using SIP and RTSP Kundan Singh and Henning Schulzrinne, Columbia University • Agenda • Introduction • Requirements • Architecture • Issues • Implementation • Q/A
Dial 853-8119 Phone is ringing Disconnect Alice 939-7063 Bob 853-8119 .. The person is not available now please leave a message ... ... Your voice message ... Traditional voice mail system Bob can listen to his voice mails by dialing some number.
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, VoIP, 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., RealPlayer • Large-scale RTSP MoD servers exist. • Easy integration with web, email, video and fax. • Access from PSTN using a gateway.
Bob INVITE bob@phone1.office.com phone1.office.com INVITE bob@office.com REGISTER bob@vm.office.com Alice sipd INVITE bob@vm.office.com Architecture 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. SIP proxy forks the request to Bob’s phone as well as to a voicemail server.
Bob phone1.office.com; CANCEL 200 OK Alice sipd 200 OK RTP/RTCP SETUP Architecture v-mail vm.office.com; After 10 seconds vm contacts the RTSP server for recording. vm accepts the call. Sipd cancels the other branch and ... rtspd ...accepts the call from Alice. Now user message gets recorded
Bob phone1.office.com Email to bob@office.com Alice sipd Architecture BYE RTP 200 OK 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.
Bob phone1.office.com INVITE bob-526156-retrieve@vm.office.com Alice sipd Quick-time RTSP SETUP/PLAY Architecture RTP v-mail vm.office.com Bob can listen to voice mail using either an RTSP client like QuickTime or ... ...by calling the v-mail using SIP. rtspd …or by visiting his web-based voicemail account
ArchitectureAlternatives • 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, POP3
Implementation • Prototype system. • Recording and playback using .au files. http://www.cs.columbia.edu/vmail
ImplementationFeatures • 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.
ImplementationFuture • 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.
e*phone Internet sipd sipd rtspd rtspd sipum sipum ConclusionWide range of applicability Campus/corporate network External application service provider Within a domain