Goip trunk unregisteres after registration

I configured Freepbx server and connected four trunks (cisco spa8800) to it, they works just fine, but when i tried to configure goip1 as trunk i see that goip unregisters after being registered for 1 second, what could it be?

What i see on my asterisk log:

-- Registered SIP '905' at [goip ip address]
-- Unregistered SIP '905'

My freepbx trunk configuration:

trunk name: 905
peer details:
    host=dynamic
    username=905
    password=password
    type=friend
    nat=no
    dtmfmode=auto
    qualify=yes
    canreinvite=no
    disallow=all
    allow=alaw&ulaw&g729

My goip configuration:

Endpoint type:     SIP Phone
Config Mode:       Single Server Mode
Phone number:      905
Display name:      905
Authentication id: 905
Password:          password
SIP Proxy:         [asterisk ip]
SIP Registrar:     [asterisk ip]
Re-register period: 30

Why goip unregisters after registration?