these requirements, but it also needs to present a uniform approach for the
three message store access phases:
- User and system access for managing the “mailbox”
- Message deposit
- Message retrieval
Architecture and Operation
An example is appropriate at this point to illustrate the open architecture for
unified messaging. This architecture is based entirely on the standard proto-
cols SIP, SMTP, HTTP, and RTSP. An example illustrating the operation of the
open architecture for unified messaging is shown in Figure 12.1.
Figure 12.1 Example of open standards based unified messaging operation
1 PSTN or
mobile cell
VoIP
Gateway
SIP Server
3 Call is forked to phone
and to UM server
4 Called party
does not answer
Message
retrieval by
voice
Web retrieval and
playback using RTSP
5 Message
store takes
call after
timeout
7 NOTIFY
6 e-mail notification
UM Server
Unified Message Store
2
3
3
Voicemail and Universal Messaging 211