Transcript Voice-mail System using SIP/RTSP

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, 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.
Architecture
Bob
INVITE [email protected]
phone1.office.com
INVITE
[email protected]
REGISTER [email protected]
Alice
INVITE [email protected]
vm.office.com
The voice mail server registers with the SIP proxy, sipd, on behalf of every user.
Alice calls [email protected] through SIP proxy.
SIP proxy forks the request to Bob’s phone as well as to a voicemail server.
Architecture
Bob
phone1.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
phone1.office.com
Email to [email protected]
BYE
Alice
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.
Architecture
Bob
phone1.office.com
INVITE [email protected]
Alice
RTP
Quick-time
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.
…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, POP3
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
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•
•
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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
sipum
rtspd
Within a domain
External application
service provider