Sip agent registers with asterisk IP causing loop!

Hello everyone, i am trying to register a sip-voip v1.2 client from touchmods running on an ipod touch to my asterisk v1.4.0.
It does register to asterisk, however asterisk console shows asterisk own ip instead of sip-voip client.
Asterisk IP is: 192.168.15.2
sip-voip IP is: 192.168.15.233

Logs:

ASTERISK*CLI> sip show peers
Name/username Host Dyn Nat ACL Port Status
1026/1026 192.168.15.2 D 5060 OK (1 ms)

This is the registration dialog:

U 192.168.15.233:5060 -> 192.168.15.2:5060
REGISTER sip:192.168.15.2 SIP/2.0…Via: SIP/2.0/UDP 192.168.15.233:5060;rport;branch=z9hG4bKPj009b0000000ba7410000…Max-Forward
s: 70…From: sip:1026@192.168.15.2;tag=009b0000000aa7410000…To: sip:1026@192.168.15.2…Call-ID: 009b00000009a7410000…CSeq
: 53269 REGISTER…User-Agent: SIP-VoIP 1.1…Contact: sip:1026@192.168.15.2…Expires: 1800…Content-Length: 0…

U 192.168.15.2:5060 -> 192.168.15.233:5060
SIP/2.0 100 Trying…Via: SIP/2.0/UDP 192.168.15.233:5060;branch=z9hG4bKPj009b0000000ba7410000;received=192.168.15.233;rport=506
0…From: sip:1026@192.168.15.2;tag=009b0000000aa7410000…To: sip:1026@192.168.15.2…Call-ID: 009b00000009a7410000…CSeq: 53
269 REGISTER…User-Agent: Asterisk PBX…Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY…Supported: replaces
…Contact: sip:1026@192.168.15.2…Content-Length: 0…

U 192.168.15.2:5060 -> 192.168.15.233:5060
SIP/2.0 200 OK…Via: SIP/2.0/UDP 192.168.15.233:5060;branch=z9hG4bKPj009b0000000ba7410000;received=192.168.15.233;rport=5060…F
rom: sip:1026@192.168.15.2;tag=009b0000000aa7410000…To: sip:1026@192.168.15.2;tag=as1932b891…Call-ID: 009b00000009a741000
0…CSeq: 53269 REGISTER…User-Agent: Asterisk PBX…Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY…Supporte
d: replaces…Expires: 1800…Contact: sip:1026@192.168.15.2;expires=1800…Date: Wed, 20 Aug 2008 19:15:05 GMT…Content-Length:
0…

This is what I get when dialing sip-voip extension # 1026:

-- Called 1026> exit
-- Got SIP response 482 "Loop Detected" back from 192.168.15.2
-- Now forwarding Local/1026@corporate-dial-ef90,2 to 'Local/1026@corporate-dial' (thanks to SIP/1026-0ac29278)
-- Executing [1026@corporate-dial:1] Dial("Local/1026@corporate-dial-f1fe,2", "SIP/1026|30|CTtWw") in new stack

Any clue?
Best regards,
Pablo