[SIPForum-discussion] Paging/intercom with SIP?

[Matt Vlasach]

Hi Benjamin,

Paging/Intercom isn't defined explicitly in the SIP protocol, however there is an RFC that outlines the SIP standard for managing Answer Modes for compliant SIP endpoints, one of which is an "Auto Answer" capability.  This essentially takes the device off hook and into speaker phone mode, which is essentially what you are looking to do.

Check out RFC 5373: http://www.rfc-archive.org/getrfc.php?rfc=5373

All that said, I have not seen this deployed in practice (for whatever reason).  What I have seen is with Polycom devices, an "Alert-Info" SIP Header is added to outbound INVITE packets that instruct the phone to go into speaker phone mode.  There are several parameters that have to be set up on the phone, and these settings need to be enabled/tuned because usually they are disabled by default.  Of course, this is just for Polycoms, so other endpoints likely will not work when you send that message to them.

In your android environment, this RFC may be implemented and you may be in luck, but just keep in mind the security implications when designing the protocol.

Good luck!

Best,

Matt Vlasach
Pacific Swell Networks, Inc.
Innovating IP Telephony and Unified Communications Solutions
http://pacificswell.com
http://www.twitter.com/PacSwellNet

email | matt.vlasach at pacificswell.com
tel | 310.598.3017
contacts |  http://mattvlasach.tel

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On Apr 2, 2010, at 8:21 AM, Benjamin Yeatts-Lonske wrote:

> Hello, can anyone tell me if paging/intercom is defined as part of SIP
> standard? We have a system where a SIP client & server will be running
> on a PC base station, and SIP clients will be running on Android
> mobiles. We'd like the base station operator to be able to do paging,
> but the Sipdroid app does not support this. We can work to add it, if
> it is part of the protocol.
> 
> Thanks,
> Ben
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