The INVITEs sent by the Gigaset PBX are not correct. In the INVITE in the example below, it shows Digest username="plaintext" which is incorrect. Instead of plaintext the account ID should be here. A solution for this is not yet known.
INVITEsip:0612345678@sipproxy.voipgrid.nl SIP/2.0
Via: SIP/2.0/UDP 12.34.56.78:5060;branch=z9hG4bK5aadb68d;rport
From: "Gigaset" <sip:123456789@12.34.56.78>;tag=as4f889712
To: <sip:0612345678@ha.voys.nl>
Contact: <sip:123456789@12.34.56.78>
Call-ID: 51a15944482e3ad35cd0873468b9a173@12.34.56.78
CSeq: 103 INVITE
User-Agent: Gigaset PRO
Max-Forwards: 70
Proxy-Authorization: Digest username="plaintext", realm="voipgrid.nl", algorithm=MD5, uri="sip:0612345678@sipproxy.voipgrid.nl", nonce="534549c80001339363234e2f0d5f1913d74932e180eaf28d", response="6250fec26c5f3454c7e09ebfaa893691"
Date: Wed, 09 Apr 2014 13:22:50 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces
privacy: id
P-Preferred-Identity: "anonymous" <sip:0@starface.de>
Content-Type: application/sdp
Content-Length: 213
v=0
o=root 2559 2560 IN IP4 12.34.56.78
s=session
c=IN IP4 12.34.56.78
t=0 0
m=audio 16530 RTP/AVP 8 101
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv