Failed to authenticate

Hello Guys.
Just installed freepbx into hyperv windows server 2012, i followed all the instruction fo setting up but after i try to register the sip into the zoiper account i a unable to complete.
Checked the logs and i see the following logs. any suggestion?

[2017-10-06 15:13:10] NOTICE[18495] res_pjsip/pjsip_distributor.c: Request ‘REGISTER’ from ‘sip:[email protected]’ failed for ‘’ (callid: Mjg3YjIzYzRkMjM4ZGE3OTEwNDgwYjVlZmZlNjE1YWU.) - Failed to authenticate