[OpenSER-Users] SoftPhone keep sending REGISTER message

[Andhika Gannesha Gemilang]

Hi,
im using Linphone, when im about to connect using ipv6 address, i
found that my softphone keep sending REGISTER message;
-------------------------------------------------
11:54:49.475240 IP6 2004:fa22:337:4::82.sip > 2004:fa22:337:4::81.sip:
SIP, length: 400
`......@ ..".7.......... ..".7.................aREGISTER
sip:[2004:fa22:337:4::81] SIP/2.0
Via: SIP/2.0/UDP [2004:fa22:337:4::82]:5060;branch=z9hG4bK679317669
From: <sip:2002@[2004:fa22:337:4:]:81>;tag=618703948
To: <sip:2002@[2004:fa22:337:4:]:81>
Call-ID: 1861704303 at 2004:fa22:337:4::82
CSeq: 1 REGISTER
Contact: <sip:2002@[2004:fa22:337:4::82]:5060>
Max-Forwards: 70
User-Agent: Linphone-1.7.1/eXosip
Expires: 900
Content-Length: 0


11:54:49.475635 IP6 2004:fa22:337:4::81.sip > 2004:fa22:337:4::82.sip:
SIP, length: 437
`......@ ..".7.......... ..".7..................SIP/2.0 200 OK
Via: SIP/2.0/UDP
[2004:fa22:337:4::82]:5060;branch=z9hG4bK679317669;received=2004:FA22:337:4:0:0:0:82
From: <sip:2002@[2004:fa22:337:4:]:81>;tag=618703948
To: <sip:2002@[2004:fa22:337:4:]:81>;tag=9bf42f041e5ea2673c94775a0faadb8b.a53a
Call-ID: 1861704303 at 2004:fa22:337:4::82
CSeq: 1 REGISTER
Contact: <sip:2002@[2004:fa22:337:4::82]:5060>;expires=892
Server: OpenSER (1.3.0-notls (i386/linux))
Content-Length: 0
-------------------------------------------------------------
the softphone continue to sending REGISTER even after receiving 200 OK...

until the server send 400 Bad Request;
----------------------------------------------------------
11:58:29.577922 IP6 2004:fa22:337:4::81.sip > 2004:fa22:337:4::82.sip:
SIP, length: 486
`......@ ..".7.......... ..".7..................SIP/2.0 400 Bad Request
Via: SIP/2.0/UDP
[2004:fa22:337:4::82]:5060;branch=z9hG4bK728798624;received=2004:FA22:337:4:0:0:0:82
From: <sip:2002@[2004:fa22:337:4:]:81>;tag=618703948
To: <sip:2002@[2004:fa22:337:4:]:81>;tag=9bf42f041e5ea2673c94775a0faadb8b.3e2a
Call-ID: 1861704303 at 2004:fa22:337:4::82
CSeq: 2 REGISTER
Contact: <sip:2002@[2004:fa22:337:4::82]:5060>;expires=873
P-Registrar-Error: Invalid CSeq number
Server: OpenSER (1.3.0-notls (i386/linux))
Content-Length: 0
-------------------------------------------------------

PS: the softphone works fine on ipv4

any suggestion would be very helpful...