Pjsip rejected, but calls coming in

hi,
i am setting freepbx with pjsip behind two firewalls. that is really annoying, but i have no other chance.

in freepbx i set up a pjsip trunk to our telco provider. the registration seem to fail, status is rejected, but call is ocming in. can anyone explain, what is happening here?
besides this we have another trunk to another provider, which is working fine…?

freepbx*CLI> pjsip show registrations

<Registration/ServerURI…> <Auth…> <Status…>

pjsip_sipgate/sip:sipgate.de:5060 pjsip_sipgate Registered
pjsip_telekom_69xxxx/sip:tel.t-online.de:5060 pjsip_telekom_69xxxx Unregistered

freepbx*CLI> pjsip show registrations

<Registration/ServerURI…> <Auth…> <Status…>

pjsip_sipgate/sip:sipgate.de:5060 pjsip_sipgate Registered
pjsip_telekom_69xxxx/sip:tel.t-online.de:5060 pjsip_telekom_69xxxx Unregistered

[2016-10-07 21:05:55] WARNING[29184]: res_pjsip_outbound_registration.c:761 schedule_retry: No response received from ‘sip:tel.t-online.de:5060’ on registration attempt to ‘sip:[email protected]:5060’, retrying in ‘60’
– Contact pjsip_telekom_69xxxx/sip:[email protected]:5060 is now Reachable. RTT: 432.054 msec
== Endpoint pjsip_telekom_69xxxx is now Reachable
freepbx*CLI> pjsip show registrations

<Registration/ServerURI…> <Auth…> <Status…>

pjsip_sipgate/sip:sipgate.de:5060 pjsip_sipgate Registered
pjsip_telekom_69xxxx/sip:tel.t-online.de:5060 pjsip_telekom_69xxxx Rejected

-- Contact pjsip_sipgate/sip:[email protected]:5060 is now Unreachable.  RTT: 0.000 msec
-- Executing [02xxx69xxxx@from-pstn:1] Set("PJSIP/pjsip_telekom_69xxxx-00000001", "__DIRECTION=INBOUND") in new stack
-- Executing [02xxx69xxxx@from-pstn:2] Gosub("PJSIP/pjsip_telekom_69xxxx-00000001", "sub-record-check,s,1(in,02xxx69xxxx,dontcare)") in new stack

[…]

any explanation for this?