[OpenSIPS-Users] no audio from caller when using nathelper

Bogdan-Andrei Iancu bogdan at voice-system.ro
Tue Apr 7 17:55:37 CEST 2009


Hi Gabriel,

So you are not using rtpproxy, but rely on the fact that * is all the 
time public. In this case, audio from caller to * should work all the 
time as the destination is public (of course, if the caller does send 
RTP). For the other way around, you can be sure * sends RTP to the 
public IP of the NAT (of the client) by doing fix_nated_sdp("1") for the 
invite - this will force the COMEDIA support in *.

Anyhow, for RTP nat traversal to work, it is mandatory for the party 
behind the nat to start sending RTP (to open the NAT). If the natted 
party will send no RTP, there will be no audio at all.

Regard,
Bogdan

Gabriel Bermudez wrote:
> Hi everyone,
>
> I'm using the nathelper and dispatcher module to send calls to an 
> Asterisk server.  I'm using the Asterisk as a SIP to H.323 converter 
> because our PSTN gateway only speaks H.323
> For some reason *sometimes* the caller does not send RTP traffic to the 
> opensips (one way audio).  The caller's UA is behind a NAT, but it 
> doesn't gets detected as a nated UA, so the RTP flow is between the 
> client's public IP and the Asterisk public IP (rtpproxy is not used).  
> I'm not sure if this problems happens also with UAs that get NAT 
> detected (not seen it happen).  I used tshark to capture the invite from 
> an undetected NAT UA (changed the UA ip with *uac_public_ip* and 
> opensip's ip with *opensips_public_ip*)
>
> Session Initiation Protocol
>     Request-Line: INVITE sip:0059389954277 at opensips_public_ip SIP/2.0
>         Method: INVITE
>         [Resent Packet: False]
>     Message Header
>         To: <sip:0059389954277 at opensips_public_ip>
>             SIP to address: sip:0059389954277 at opensips_public_ip
>         Accept: 
> application/dtmf-relay,application/sdp,text/plain,message/sipfrag,application/sip
>         User-Agent: YV1/1.2.0
>         Via: SIP/2.0/UDP uac_public_ip:10759;rport;branch=z9hG4bK474bfa15
>             Transport: UDP
>             Sent-by Address: uac_public_ip
>             Sent-by port: 10759
>             RPort: rport
>             Branch: z9hG4bK474bfa15
>         From: "710406702"<sip:710406702 at opensips_public_ip>;tag=41a8c40d
>             SIP Display info: "710406702"
>             SIP from address: sip:710406702 at opensips_public_ip
>             SIP tag: 41a8c40d
>         Allow: UPDATE,INFO,PRACK,REFER,NOTIFY,INVITE,ACK,OPTIONS,BYE,CANCEL
>         Allow-Events: refer
>         Call-ID: 27f2a0fb-390a1f2a-5e9e57cd-1ee3a7b0 at uac_public_ip
>         Max-Forwards: 70
>         Contact: <sip:710406702 at uac_public_ip:10759>
>             Contact Binding: <sip:710406702 at uac_public_ip:10759>
>                 URI: <sip:710406702 at uac_public_ip:10759>
>                     SIP contact address: sip:710406702 at uac_public_ip:10759
>         Session-Expires: 1800
>         Content-Length: 313
>         Content-Type: application/sdp
>         Supported: timer,100rel,join,tdialog,replaces,norefersub,histinfo
>         CSeq: 57741 INVITE
>             Sequence Number: 57741
>             Method: INVITE
>     Message Body
>         Session Description Protocol
>             Session Description Protocol Version (v): 0
>             Owner/Creator, Session Id (o): ipr1B24E8AED4 4453550 4453550 
> IN IP4 uac_public_ip
>                 Owner Username: ipr1B24E8AED4
>                 Session ID: 4453550
>                 Session Version: 4453550
>                 Owner Network Type: IN
>                 Owner Address Type: IP4
>                 Owner Address: uac_public_ip
>             Session Name (s): -
>             Connection Information (c): IN IP4 uac_public_ip
>                 Connection Network Type: IN
>                 Connection Address Type: IP4
>                 Connection Address: uac_public_ip
>             Time Description, active time (t): 0 0
>                 Session Start Time: 0
>                 Session Stop Time: 0
>             Media Description, name and address (m): audio 10760 RTP/AVP 
> 0 8 4 18 101
>                 Media Type: audio
>                 Media Port: 10760
>                 Media Proto: RTP/AVP
>                 Media Format: ITU-T G.711 PCMU
>                 Media Format: ITU-T G.711 PCMA
>                 Media Format: ITU-T G.723
>                 Media Format: ITU-T G.729
>                 Media Format: 101
>             Media Attribute (a): rtpmap:0 PCMU/8000
>                 Media Attribute Fieldname: rtpmap
>                 Media Format: 0
>                 MIME Type: PCMU
>             Media Attribute (a): rtpmap:8 PCMA/8000
>                 Media Attribute Fieldname: rtpmap
>                 Media Format: 8
>                 MIME Type: PCMA
>             Media Attribute (a): rtpmap:4 G723/8000
>                 Media Attribute Fieldname: rtpmap
>                 Media Format: 4
>                 MIME Type: G723
>             Media Attribute (a): rtpmap:18 G729/8000
>                 Media Attribute Fieldname: rtpmap
>                 Media Format: 18
>                 MIME Type: G729
>             Media Attribute (a): rtpmap:101 telephone-event/8000
>                 Media Attribute Fieldname: rtpmap
>                 Media Format: 101
>                 MIME Type: telephone-event
>             Media Attribute (a): ptime:20
>                 Media Attribute Fieldname: ptime
>                 Media Attribute Value: 20
>             Media Attribute (a): fmtp:101 0-16
>                 Media Attribute Fieldname: fmtp
>                 Media Format: 101 [telephone-event]
>                 Media format specific parameters: 0-16
>             Media Attribute (a): fmtp:4 ptime=30;bitrate=6.3
>                 Media Attribute Fieldname: fmtp
>                 Media Format: 4 [telephone-event]
>                 Media format specific parameters: ptime=30
>                 Media format specific parameters: bitrate=6.3
>
> I really don't find anything wrong with it but I'm no SIP expert.  Can 
> some one help me with some pointers.
> Thanks for you help.
>
> Regards,
>
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