[OpenSIPS-Users] Registration - strange behaviour

[Carlo Dimaggio]

Hi all,

I have a natted ATA that is trying to register to my opensips. The  
registration comes from a port different from the standard 5060.
The problem is that the opensips reply to the 5060 and not to the  
receiving port (45900). I don't understand this behaviour....

U 200.200.200.200:45900 -> <IP_OPENSIPS>:5060
REGISTER sip:sip.xxx.it SIP/2.0.
Via: SIP/2.0/UDP 192.168.2.100;branch=z9hG4bK-fe05a550.
From: SPAFax1004 <sip:1004 at sip.xxx.it>;tag=b7441aad8d759152o0.
To: SPAFax1004 <sip:1004 at sip.xxx.it>.
Call-ID: 300b52dc-49189d79 at 192.168.2.100.
CSeq: 3028 REGISTER.
Max-Forwards: 70.
Contact: SPAFax1004 <sip:1004 at 192.168.2.100>;expires=3600.
User-Agent: Linksys/SPA2102-5.2.10.
Content-Length: 0.
Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER.
Supported: x-sipura, replaces.
.

#
U <IP_OPENSIPS>:5060 -> 200.200.200.200:5060		<----- should be 45900??
SIP/2.0 401 Unauthorized.
Via: SIP/2.0/UDP 192.168.2.100;branch=z9hG4bK- 
fe05a550;received=200.200.200.200.
From: SPAFax1004 <sip:1004 at sip.xxx.it>;tag=b7441aad8d759152o0.
To: SPAFax1004 <sip: 
1004 at sip.xxx.it>;tag=c97b4d1cb1f3d0da549e06a8d482ef63.29be.
Call-ID: 300b52dc-49189d79 at 192.168.2.100.
CSeq: 3028 REGISTER.
WWW-Authenticate: Digest realm="sip.xxx.it",  
nonce="4ae82d72000005d60d2de8569cda129f11de143bdaf8a3b7", qop="auth".
Server: VoIP SIPServer.
Content-Length: 0.


What could be the problem?

Thanks and regards,
Carlo