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Hi!

We have a few Snom 710 that sometimes respond with "505 Version Not Supported"  to a "401 Unauthorized" asking for authentication when the phone is sending an INVITE, SUBSCRIBE etc. 

This can for example make outgoing calls from the phone fail.

I can't figure out what the problem is here, any ideas?

SIP log from the server: 

[Mar 14 11:09:49] VERBOSE[17435] chan_sip.c:
<--- SIP read from TLS:194.218.237.146:53099 --->
INVITE sip:123456@tele.favoptic.com;user=phone SIP/2.0
Via: SIP/2.0/TLS 194.218.237.146:53999;branch=z9hG4bK-l21ixd2qdvhu;rport
From: "Erik" <sip:304@tele.favoptic.com>;tag=qtexasdfa
To: <sip:123456@tele.favoptic.com;user=phone>
Call-ID: 313535323535383138313235343938-49ehpng57tfy
CSeq: 1 INVITE
Max-Forwards: 70
User-Agent: snom710/8.9.3.80
Contact: <sip:304@194.218.237.146:53999;transport=Tls>;reg-id=1
X-Serialnumber: 00041376F522
P-Key-Flags: resolution="31x13", keys="4"
Accept: application/sdp
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO, UPDATE
Allow-Events: talk, hold, refer, call-info
Supported: timer, 100rel, replaces, from-change
Session-Expires: 3600
Min-SE: 90
Authorization: Digest username="304",realm="asterisk",nonce="5e587226",uri="sip:56482300@tele.favoptic.com;user=phone",response="1b96371a87abfe6789cdb4db647681b9",algorithm=$
Content-Type: application/sdp
Content-Length: 439

v=0
o=root 456887773 456887773 IN IP4 194.218.237.146
s=call
c=IN IP4 194.218.237.146
t=0 0
m=audio 52802 RTP/AVP 9 0 8 3 99 112 18 101
a=direction:both
a=rtpmap:9 G722/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:3 GSM/8000
a=rtpmap:99 G726-32/8000
a=rtpmap:112 AAL2-G726-32/8000
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
a=rtcp:11041
a=sendrecv
<--- Reliably Transmitting (NAT) to 194.218.237.146:53099 --->
SIP/2.0 401 Unauthorized
Via: SIP/2.0/TLS 194.218.237.146:53999;branch=z9hG4bK-l21ixd2qdvhu;received=194.218.237.146;rport=53099
From: "Erik" <sip:304@tele.favoptic.com>;tag=qtexdctx8i
To: <sip:123456@tele.favoptic.com;user=phone>;tag=as58053d8e
Call-ID: 313535323535383138313235343938-49ehpng57tfy
CSeq: 1 INVITE
Server: Asterisk PBX 13.1.0~dfsg-1.1ubuntu4.1
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH, MESSAGE
Supported: replaces, timer
WWW-Authenticate: Digest algorithm=MD5, realm="asterisk", nonce="22460373"
Content-Length: 0
<------------>
<--- SIP read from TLS:194.218.237.146:53099 --->
SIP/2.0 505 Version Not Supported
Via: SIP/2.0/TLS 194.218.237.146:53999;branch=z9hG4bK-l21ixd2qdvhu;received=194.218.237.146;rport=5061;received=79.136.114.144
From: "Erik" <sip:304@tele.favoptic.com>;tag=qtexdctx8i
To: <sip:56482300@tele.favoptic.com;user=phone>;tag=as58053d8e
Call-ID: 313535323535383138313235343938-49ehpng57tfy
CSeq: 1 INVITE
User-Agent: snom710/8.9.3.80
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO, UPDATE
Allow-Events: talk, hold, refer, call-info
Supported: timer, 100rel, replaces, from-change
Content-Length: 0