No registration

This probably is a newbie problem but seems difficult for me.
I start the freePBX and I’m trying to configure to simple extensions but I got some issues on it.
I’m using zoiper and I did this:
1- Create 2 new IAX extensions, eg. 101 102 with their respective secrets, no other parameter changed or edited.
2- Create in zoiper a new IAX account and I put the parameters:
–Server Hostname :ip of Rpi–
–Username: 102
–Password: 123456qw
–Caller ID name: Empty
–Caller ID number: Empty

3- Then in the zoiper log I got this message " 15:41:26 Failed registration for ‘@’ with cause ‘facility rejected’ "

Any help would be much appreciated