[Users] 180 Ringing / 183 Session Progress

[Klaus Darilion]

And it is also common that a gateway sends both - 180 (ISDN Alerting) 
and 183 (ISDN Progress with inband audio available)

regards
klaus

Jerome Martin wrote:
> Also note that on ISDN/SIP gateways, you often have many options to
> fine-tune this. Like progress indicators mappings, play local tone or
> just forward distant, etc.
> 
> 
> On Tue, 2007-02-06 at 11:17 +0100, Atle Samuelsen wrote:
>> Hi Sam,
>>
>> * Sam Lee <sam.lee at super.net.sg> [070206 11:09]:
>>> Hey Guys,
>>>  
>>> Is it mandatory for SIP servers to generate to UA 180 Ringing to inform
>>> them that the called party is now ringing ?
>> No
>>>  
>>> The reason i'm asking is because I am seeing strange results using
>>> different UAs.
>>>  
>>> Using SIP clients to call out , instead of seeing 180 Ringing , i see
>>> 183 session progress even before call was picked up.
>> This is nothing wrong with this :)
>>>  
>>> On some sip client , ring back can be heard.
>> good, they support early media
>>> On some others , ring back cannot be heard.
>> Bad,, they do not support Early media
>>>  
>>> Is there any reason to suspect that these UAs needs to receive 180
>>> Ringing before generating any ringback ?
>> In general: 
>> 180 == Generate Local Ringback.
>> 183 == get RTP from callee, and play it (often used for network
>> announcements, calls to gSM and simular)
>>
>> - Atle
>>>  
>>> Regards,
>>> Sam
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>>
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> 
> 
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-- 
Klaus Darilion
nic.at