One user, Mark, has a Nokia phone which he tries from work and from home. At work, it works fine, when he gets at home and tries there, it no longer works. When he left his home this morning, he left a sip phone connected. When he got to work, he fired up his Nokia. I realise that we're not using the same phone in this test but it's all we had for now.

Now I see him connected twice on the SBC's.
I noticed that only his work connection has a public IP, all of the other users seem to have a private IP. I could send all of this unedited but prefer to do it in private email only. We also noticed that only his work information contains an rport, none of the others do.
The users had not made changes to their firewalls and it is also unlikely that all of them just happen to be having this problem at the same time because of their firewalls. This problem is only manifesting itself with calls being made to phones registered on the sbc's. Phone to phone internally works as do public to internal phones and vise versa.

I did capture some logs of a call being made but I would have to edit so much of it that it didn't make sense to post this just yet in case the answer is already in this port.

His Nokia From Work;
sip:3105 at mydomain dot com;user=phone sip:3105@xxx.xxx.17.98:47456;transport=UDP 1112
His Grandstream phone at Home;
sip:3105 at mydomain dot com;user=phone sip:3105@192.168.0.2:5060;transport=udp;user=phone 3359

This shows three other remotes which are also authenticated but cannot receive calls;
sip:3101 at mydomain dot com sip:3101@192.168.1.101:52198;rinstance=961d3ce1cb016f3c 2984
sip:3100 at mydomain dot com sip:3100@192.168.1.108:5060 1614
sip:2824 at mydomain dot com;user=phone sip:2824@192.168.1.101:5060;transport=udp;user=phone 776

This is what the above users grandstream connection looks like from home;

SIP/2.0 200 OK
From: "Mark" <sip:3105 at mydomain dot com;user=phone>;tag=1ad6ef2551fade118180e0db5fc215bd
To: <sip:3105 at mydomain dot com;user=phone>;tag=412776091
Via: SIP/2.0/UDP 192.168.10.6:5060;branch=z9hG4bK34d0ef2551fade118180e0db5fc215bd;uas-addr=xxx.xxx.143.244
CSeq: 14641 OPTIONS
Call-ID: 26365a46-50fa-de11-984d-e0db5fc215bd
Contact: <sip:3105@192.168.0.2:5060;transport=udp;user=phone>
User-Agent: Grandstream GXV3000 1.2.1.13
Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, OPTIONS, INFO, SUBSCRIBE, UPDATE, PRACK, MESSAGE
Supported: replaces, timer, 100rel, path
Content-Length: 0

This is what his Nokia connection looks like from work;

SIP/2.0 200 OK
From: <sip:3105 at mydomain dot com>;tag=qv5tjrkl19hc6pkp0gb3
To: <sip:3105 at mydomain dot com>;tag=1433925857
Via: SIP/2.0/UDP xxx.xxx.17.98:47456;branch=z9hG4bK7lgvti7up1rsn2ppv3v4j4b;rport=47456;received=xxx.xxx.17.98
CSeq: 1445 REGISTER
Call-Id: m4kvzwMJoIc9bwgmd9QVMQ4N8dR2Ta
Contact: <sip:3105@67.139.17.98:47456;transport=UDP>;expires=3600
Date: Thu, 07 Jan 2010 23:39:03 GMT
User-Agent: sipXecs/4.0.4 sipXecs/registry (Linux)
Expires: 2724
Accept-Language: en
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, REGISTER, SUBSCRIBE
Supported: gruu, path
Content-Length: 0

Two other remote which cannot take calls;

SIP/2.0 200 OK
From: "remote 3" <sip:2824 at mydomain dot com;user=phone>;tag=a49c26f252fade119daf8cbccc4fbb29
To: <sip:2824 at mydomain dot com;user=phone>;tag=1827336327
Via: SIP/2.0/UDP 192.168.10.5:5060;branch=z9hG4bKb49626f252fade119daf8cbccc4fbb29;uas-addr=xxx.xxx.218.229
CSeq: 14626 OPTIONS
Call-ID: cc25b698-52fa-de11-9306-8cbccc4fbb29
Contact: <sip:2824@192.168.1.101:5060;transport=udp;user=phone>
User-Agent: Grandstream GXV3000 1.2.1.13
Allow: INVITE, ACK, CANCEL, BYE, NOTIFY, REFER, OPTIONS, INFO, SUBSCRIBE, UPDATE, PRACK, MESSAGE
Supported: replaces, timer, 100rel, path
Content-Length: 0

SIP/2.0 200 OK
From: "Glen" <sip:3100 at mydomain dot com>;tag=acdb737059fade119daf8cbccc4fbb29
To: "Glen" <sip:3100 at mydomain dot com>;tag=4f1e3d94e167f541i0
Via: SIP/2.0/UDP 192.168.10.5:5060;branch=z9hG4bK3ed6737059fade119daf8cbccc4fbb29;uas-addr=xxx.xxx.247.97
CSeq: 14759 OPTIONS
Call-ID: fe109171-54fa-de11-9306-8cbccc4fbb29
Server: Linksys/SPA941-5.1.8
Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER
Supported: replaces
Content-Length: 0

I was also wondering if my vyatta/opensbc servers could be set up to handle incoming for both systems. I recall you mentioning, I think in this thread, that I could even run two instances on two different ports. Would it be simpler to have just one instance which handles both, if possible.

Mike