[SIPForum-discussion] SIP-T

WIGNELL, Clifford (Clifford) cwignell at alcatel-lucent.com
Mon May 19 21:43:12 UTC 2008

Hello group,

This I think is true to some extent, but I would not expect it to be a global yes; the device originating the SIP-T (or SIP-I) will expect ISUP to be present and unless written to generate default ISUP values it should generate an error. The actual behaviour will depend on how the device at the SIP-T/I end was designed.

The devices I have worked on would not bring a session up in this case as SIP-T/I is normally configured as a trunk (i.e. PSTN->ISUP->SIP-T->IP->SIP-TISUP->PSTN). However the devices I have worked on allow you to configure multiple SIP interfaces on the on physical port so the normal Config in this case is to configure a SIP interface and a SIP-T interface.

The ISUP information is normally used in the MGC-F to populate the out going (to PSTN) ISUP messages and the incoming ISUP is put in the SIP-T body. SIP to SIP-T would loose the ISUP information; however you could (if you were building one) have the MGC-F put in default values but this would defeat the purpose of having SIP-T or SIP-I for that matter. Some MGC’s on the market can do this.

Best regards

Cliff Wignell
-----Original Message-----
From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Eric Burger
Sent: Tuesday, 20 May 2008 12:31 AM
To: Zei Ci
Cc: discussion at sipforum.org
Subject: Re: [SIPForum-discussion] SIP-T

Of course.  A device that does not understand the ISUP MIME type will  
happily connect.  Of course, any ISUP information that you may think  
is important will be lost.  However, the session should still start.

That, of course, assumes that the non-RFC 3372 compliant device is  
still RFC 3261 compliant and that it doesn't do something silly like  
core dump when it gets a multi-part MIME body.  Yes, we see that at  

On May 19, 2008, at 4:05 AM, Zei Ci wrote:

> Dear experts,
>   SIP can communicate with SIP-T?
> many thanks
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