[Serusers] How to force IPtel.org SIP proxy not to include RTP proxy in Media path (achive peer-to-peer flow)

[Jan Janak]

Jiri Kuthan wrote:
> At 08:12 04/03/2008, girish kumar wrote:
>> Hi,
>>
>> I have 2 SIP based softphones (Xlite) registered on
>> IPtel.org SIP service and testing the calls among
>> them. These 2 softphones are behind different NAT and
>> IPtel.org SIP proxy is replacing the SDP connection
>> details in Call setup message (Invite and 200 OK) with
>> RTPproxy IP/ports. Hence, RTPproxy is relaying the
>> Voice media stream among them during the call.
>>
>> Although, both the softphones are behind different NAT
>> address but these are not Symmetric NATs and hence RTP
>> can directly flow between these softphone using STUN
>> discovery.
> 
> That's what I'm not sure about. If they were using STUN,
> iptelorg:5060 should not have detected them as natted.
> Any insight in this?
> 
> 
>> Is it possible to disable the RTP proxy behaviour of
>> IPtel.org SER server for these 2 softphones through
>> some configuration changes or any special header
>> parameter in call setup message? 
>>
>> In User Management web interface of IPtel.org, there
>> is a option to specify the connectivity realm for a
>> user account under My Account -> Other tab.
>>
>> The description of this field is "connectivity realm -
>> behind the same NAT or possibility to communicate
>> directly". I believe this field is playing some part
>> in NAT transversal mechanism of Iptel.org SER
>> implementation.
> 
> I think too that was thought so, but I think it is 
> unused at the moment.

  Yes, it was meant to work this way. If both phones are configured to
  be in the same connectivity realm then the server assumes that they can
  reach each other directly and it does not enforce the RTP proxy, no
  matter what does the NAT detection algorithm says.

  Unfortunately this option is not currently used in the configuration
  of the iptel.org SIP server.

  I will try to put it back as time permits (because I need it myself
  for my phones).

  Hope that helps, Jan.