[asterisk-users] pjsip direct_media=yes and "unknown" endpoints

[Daniel Tryba]

I'm trying to implement direct_media between multiple peers and an
uplink provider, all of whom have direct_media=yes configures.

For originating calls to the uplink provider direct_media=yes works like
expected. SIP flows through asterisk, rtp doesn't

SIP: enduser <-> SBC <-> asterisk 13 <-> uplink
RTP: enduser <-> SBC <-----------------> uplink

SBC matches an endpoint based on ip and dials the uplink:

-- Executing [+31xxxxxxxxx at outgoingrr:9] Dial("PJSIP/sbcs-00000092", "PJSIP/+31xxxxxxxxx at uplink") in new stack
-- Called PJSIP/+31xxxxxxxxx at uplink
-- PJSIP/uplink-00000093 is making progress passing it to PJSIP/sbcs-00000092

-- PJSIP/uplink-00000093 answered PJSIP/sbcs-00000092
-- Channel PJSIP/uplink-00000093 joined 'simple_bridge' basic-bridge <3b25c543-13a3-4d74-b2fe-7122a1cfe4a4>
-- Channel PJSIP/sbcs-00000092 joined 'simple_bridge' basic-bridge <3b25c543-13a3-4d74-b2fe-7122a1cfe4a4>
   > Bridge 3b25c543-13a3-4d74-b2fe-7122a1cfe4a4: switching from simple_bridge technology to native_rtp
   > Remotely bridged 'PJSIP/sbcs-00000092' and 'PJSIP/uplink-00000093' - media will flow directly between them
   > Remotely bridged 'PJSIP/sbcs-00000092' and 'PJSIP/uplink-00000093' - media will flow directly between them

Whoever when a terminating call comes in from the uplink provider, a sip
request is send to a redirector. The redirector has redirect_method=uri_core
configured (the only method that works for me).

-- Executing [+31xxxxxxxxx at incoming:11] Dial("PJSIP/uplink-00000094", "PJSIP/+31xxxxxxxxx at pathfinder") in new stack
-- Called PJSIP/+31xxxxxxxxx at pathfinder
-- Now forwarding PJSIP/uplink-00000094 to 'PJSIP/pathfinder/sip:+31xxxxxxxxx at sip.xxxxxx.nl' (thanks to PJSIP/pathfinder-00000095)
...
-- PJSIP/pathfinder-00000096 answered PJSIP/uplink-00000094
-- Channel PJSIP/pathfinder-00000096 joined 'simple_bridge' basic-bridge <1bf02059-ea8f-4f9c-bc33-8ae99ba45c9a>
-- Channel PJSIP/uplink-00000094 joined 'simple_bridge' basic-bridge <1bf02059-ea8f-4f9c-bc33-8ae99ba45c9a>
...
-- Channel PJSIP/pathfinder-00000096 left 'simple_bridge' basic-bridge <1bf02059-ea8f-4f9c-bc33-8ae99ba45c9a>
-- Channel PJSIP/uplink-00000094 left 'simple_bridge' basic-bridge <1bf02059-ea8f-4f9c-bc33-8ae99ba45c9a>

The request now gets routed based on a fully qualified domainname (with
NAPTR/SRV records), which ultimately resolves to an ip that is matched in the
endpoint SBC used above to originate a call.  But now the asterisk stays in the
loop regarding RTP, a simple bridge is created but never switches to direct
media.

SIP: enduser <-> uplink <-> asterisk 13 <-> pathfinder (302 redirect)

SIP: enduser <-> uplink <-> asterisk 13 <-> sip.xxxxxx.nl
RTP: enduser <-> uplink <-> asterisk 13 <-> sip.xxxxxx.nl

Anybody got an idea why the last scenario fails to work?