OK, commented out the lines of code in sofia_glue.c that run the stun test and now I see an INVITE message being sent to the trunk, however the To field is $1@10.10.7.95 instead of 58661 as I would have expected.

2008-07-31 19:26:19 [WARNING] sofia.c:75 sofia_handle_sip_r_notify() delete subscriptions for failed notify

2008-07-31 19:26:50 [NOTICE] switch_channel.c:534 switch_channel_set_name() New Channel sofia/internal/1000@10.10.4.204 [bd3a342f-9c90-5842-9399-cb276b6146e7]

2008-07-31 19:26:50 [INFO] mod_dialplan_xml.c:222 dialplan_hunt() Processing Simon FS->58661@default

2008-07-31 19:26:51 [NOTICE] switch_channel.c:534 switch_channel_set_name() New Channel sofia/nat/$1@10.10.7.95 [e7312a7e-2b59-1449-8266-c5f098ae93f0]

2008-07-31 19:26:51 [NOTICE] sofia.c:2550 sofia_handle_sip_i_state() Hangup sofia/nat/$1@10.10.7.95 [CS_CONSUME_MEDIA] [NO_ROUTE_DESTINATION]

2008-07-31 19:26:51 [INFO] mod_dptools.c:1794 audio_bridge_function() Originate Failed.  Cause: NO_ROUTE_DESTINATION

2008-07-31 19:26:51 [NOTICE] mod_dptools.c:1821 audio_bridge_function() Hangup sofia/internal/1000@10.10.4.204 [CS_EXECUTE] [NO_ROUTE_DESTINATION]

2008-07-31 19:26:51 [NOTICE] switch_core_session.c:807 switch_core_session_thread() Session 2 (sofia/nat/$1@10.10.7.95) Ended

2008-07-31 19:26:51 [NOTICE] switch_core_session.c:809 switch_core_session_thread() Close Channel sofia/nat/$1@10.10.7.95 [CS_HANGUP]

2008-07-31 19:26:51 [NOTICE] switch_core_session.c:807 switch_core_session_thread() Session 1 (sofia/internal/1000@10.10.4.204) Ended

2008-07-31 19:26:51 [NOTICE] switch_core_session.c:809 switch_core_session_thread() Close Channel sofia/internal/1000@10.10.4.204 [CS_HANGUP]