[Freeswitch-users] 486 Busy turns to 480 Temporarily Unavailable

[Peter P GMX]

Hello,

I have a strange phenomen:

When a target UA is busy, it returns "486 Busy" to Freeswitch. But 
Freeswitch then returns "480 Temporarily Unavailable" to the called party.
Where does this come from and how can I change this behaviour?

See (anonymized) SIP trace with ngrep:

UA to Freeswitch:
========================
U 2012/01/04 13:59:44.928775 <fritzbox-IP>:5060 -> <freeswitch-IP>:5080
SIP/2.0 486 Busy Here.
Via: SIP/2.0/UDP
<freeswitch-IP>:5080;rport=5080;branch=z9hG4bKNZZDv0Syp4eyr.
From: "026xxxxxxxx" <sip:026xxxxxxxx@<freeswitch-IP>>;tag=py094Kv7vr03a.
To:
<sip:069xxxxxxxx@<fritzbox-IP>;uniq=B05FE4881A55AEEB69361EFA327DB>;tag=E1C3374B97DAB2DE.
Call-ID: d0d0d057-b176-122f-1f8d-001ec9b9da3c.
CSeq: 22504928 INVITE.
User-Agent: AVM FRITZ!Box 6360 Cable 85.05.07 (Sep 14 2011).
Content-Length: 0.

Freeswitch to Caller:
========================
U 2012/01/04 13:59:44.930387 <freeswitch-IP>:5060 -> <Sip-provider-IP>:5060
SIP/2.0 480 Temporarily Unavailable.
Via: SIP/2.0/UDP <Sip-provider-IP>:5060;branch=z9hG4bK-4896-2830DFA.
From:
<sip:4926xxxxxxxx at sip.provider.de;user=phone>;tag=13517-HB-08a98588-2622da197.
To: <sip:4969xxxxxxxx@<freeswitch-IP>;user=phone>;tag=XQtc5US24QgDa.
Call-ID: 13517-SG-08a98587-0a352e121 at sip.provider.de.
CSeq: 134781549 INVITE.
User-Agent: FreeSWITCH-mod_sofia/1.0.head-git-68627e8 2011-11-21
13-52-28 -0600.
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, UPDATE, INFO,
REGISTER, REFER, NOTIFY.
Supported: precondition, path, replaces.
Allow-Events: talk, hold, refer.
Content-Length: 0.
P-Asserted-Identity: "069xxxxxxxx" <sip:069xxxxxxxx@<freeswitch-IP>>.

Best regards
Peter