[SIPForum-discussion] 180 Ringing not generated

[Kevin P. Fleming]

On 09/07/2010 02:34 AM, vidhya gopalan wrote:

> I am just a beginner in SIP. I am sending a INVITE from one of the
> endpoints, but the other endpoint doesnt send 180 Ringing back. wat
> could be the possible reason for failure.

Lack of '180 Ringing' is not necessarily any kind of failure; '180
Ringing' is not a mandatory message in SIP INVITE-created dialogs. An
endpoint can choose to send 180 provisional response based on its local
configuration, how the call is proceeding and various other factors.
Your endpoint that sent the INVITE must be prepared to accept such a
response if one arrives, but cannot rely on it always arriving.

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Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
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