[OpenSER-Users] [OT] Do ITSP SIP_PSTN gateways allow REFER?

[Klaus Darilion]

Iñaki Baz Castillo schrieb:
> El Thursday 15 November 2007 12:44:31 Klaus Darilion escribió:
>> Iñaki Baz Castillo schrieb:
>>> Hi, I will connect my OpenSer with a Nortel (SIP to PSTN gateway) for
>>> incoming/outgoings call to/from PSTN.
>>>
>>> I have a doubt: if an OpenSer user (200 at mydomain.org) receives an
>>> incoming call from gateway, could he REFER the call to 201 at mydomain.org?
>>>
>>> This is: do ITSP gateways allow REFER to SIP users subcribers to my
>>> OpenSer? I understand they could not accept REFER's to PSTN number
>>> because accounting issues (gateway UAC receving a REFER and calling to
>>> PSTN?).
>> Usually it depends on the configuration of the gateway. Thus, I would
>> add some screening of REFER and 3xx to the proxy.
> 
> Sorry Klaus, I don't understnad what you mean with "screening of REFER and 3XX 
> to the proxy", could you explain it please?

For example, if the system is a POTS replacement (no PBX feature, just 
VoIP-VoIP and VoIP-PSTN with phone calls) then I would:
1. if method==REFER
      sl_reply("403","");
2. activate a failure route and if response code = 3xx then 
sl_send_reply("500",)

If the system also offers PBX features (call transfer ...) then you can 
not just block it - but you can screen it - e.g. for REFER requests 
check if the URI in the Refer-To header does not contain premium rate 
phone numbers, or that REFERs are not sent to the gateway ...

regards
klaus


> 
> Thanks a lot.
> 
>