Cant connect from external ip , but internal ip ok

got this error:

[2011-08-18 16:05:35]
NOTICE[3331]: chan_sip.c:24170 handle_request_register: Registration from ‘"513001"sip:[email protected]:5060***.**’ failed for ‘203.153..*:55235’ - No matching peer found

i already route the ip to public ip, allow all port to the internal ip.
still got any to install or what???

any idea