Here is a failed registration:
76735483mS SIP Reg/Opt Rx: phone
REGISTER sip:10.25.3.60 SIP/2.0
Via: SIP/2.0/UDP 10.25.3.166:5070;rport;branch=z9hG4bKPj60cf955a-0698-4908-84c2-c1a2437fac60
Max-Forwards: 70
From: <sip:260@10.25.3.60>;tag=c15e0b57-eabf-47d0-ada1-8a1fc0d21d72
To: <sip:260@10.25.3.60>
Call-ID: 920a7162-7720-48c1-8b71-832fe1de14cf
CSeq: 41309 REGISTER
User-Agent: SpectralinkVersity 9540 apollo OPM1.171019.026 1.7.0.1232 9.1.18064 2020.01.10 16.38 GMT
Contact: <sip:260@10.25.3.166:5070;ob>
Expires: 300
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Content-Length: 0
76735487mS SIP Reg/Opt Tx: phone
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 10.25.3.166:5070;rport;branch=z9hG4bKPj60cf955a-0698-4908-84c2-c1a2437fac60
From: <sip:260@10.25.3.60>;tag=c15e0b57-eabf-47d0-ada1-8a1fc0d21d72
Call-ID: 920a7162-7720-48c1-8b71-832fe1de14cf
CSeq: 41309 REGISTER
User-Agent: IP Office 11.1.3.0.0 build 23
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,NOTIFY,INFO,SUBSCRIBE,REGISTER,PUBLISH
Digest nonce="d627cd51d1e8ea111418",realm="ipoffice",algorithm=MD5
Server: IP Office 11.1.3.0.0 build 23
To: <sip:260@10.25.3.60>;tag=3fcdce5726e5294e
Content-Length: 0
76736096mS SIP Reg/Opt Tx: phone
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 10.25.3.166:5070;rport;branch=z9hG4bKPj60cf955a-0698-4908-84c2-c1a2437fac60
From: <sip:260@10.25.3.60>;tag=c15e0b57-eabf-47d0-ada1-8a1fc0d21d72
Call-ID: 920a7162-7720-48c1-8b71-832fe1de14cf
CSeq: 41309 REGISTER
User-Agent: IP Office 11.1.3.0.0 build 23
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,NOTIFY,INFO,SUBSCRIBE,REGISTER,PUBLISH
Digest nonce="d627cd51d1e8ea111418",realm="ipoffice",algorithm=MD5
Server: IP Office 11.1.3.0.0 build 23
To: <sip:260@10.25.3.60>;tag=3fcdce5726e5294e
Content-Length: 0
76737007mS SIP Reg/Opt Tx: phone
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 10.25.3.166:5070;rport;branch=z9hG4bKPj60cf955a-0698-4908-84c2-c1a2437fac60
From: <sip:260@10.25.3.60>;tag=c15e0b57-eabf-47d0-ada1-8a1fc0d21d72
Call-ID: 920a7162-7720-48c1-8b71-832fe1de14cf
CSeq: 41309 REGISTER
User-Agent: IP Office 11.1.3.0.0 build 23
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,NOTIFY,INFO,SUBSCRIBE,REGISTER,PUBLISH
Digest nonce="d627cd51d1e8ea111418",realm="ipoffice",algorithm=MD5
Server: IP Office 11.1.3.0.0 build 23
To: <sip:260@10.25.3.60>;tag=3fcdce5726e5294e
Content-Length: 0
76739017mS SIP Reg/Opt Tx: phone
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 10.25.3.166:5070;rport;branch=z9hG4bKPj60cf955a-0698-4908-84c2-c1a2437fac60
From: <sip:260@10.25.3.60>;tag=c15e0b57-eabf-47d0-ada1-8a1fc0d21d72
Call-ID: 920a7162-7720-48c1-8b71-832fe1de14cf
CSeq: 41309 REGISTER
User-Agent: IP Office 11.1.3.0.0 build 23
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,NOTIFY,INFO,SUBSCRIBE,REGISTER,PUBLISH
Digest nonce="d627cd51d1e8ea111418",realm="ipoffice",algorithm=MD5
Server: IP Office 11.1.3.0.0 build 23
To: <sip:260@10.25.3.60>;tag=3fcdce5726e5294e
Content-Length: 0
76743010mS SIP Reg/Opt Rx: phone
REGISTER sip:10.25.3.60 SIP/2.0
Via: SIP/2.0/UDP 10.25.3.166:5070;rport;branch=z9hG4bKPj60cf955a-0698-4908-84c2-c1a2437fac60
Max-Forwards: 70
From: <sip:260@10.25.3.60>;tag=c15e0b57-eabf-47d0-ada1-8a1fc0d21d72
To: <sip:260@10.25.3.60>
Call-ID: 920a7162-7720-48c1-8b71-832fe1de14cf
CSeq: 41309 REGISTER
User-Agent: SpectralinkVersity 9540 apollo OPM1.171019.026 1.7.0.1232 9.1.18064 2020.01.10 16.38 GMT
Contact: <sip:260@10.25.3.166:5070;ob>
Expires: 300
Allow: PRACK, INVITE, ACK, BYE, CANCEL, UPDATE, INFO, SUBSCRIBE, NOTIFY, REFER, MESSAGE, OPTIONS
Content-Length: 0
76743014mS SIP Reg/Opt Tx: phone
SIP/2.0 401 Unauthorized
Via: SIP/2.0/UDP 10.25.3.166:5070;rport;branch=z9hG4bKPj60cf955a-0698-4908-84c2-c1a2437fac60
From: <sip:260@10.25.3.60>;tag=c15e0b57-eabf-47d0-ada1-8a1fc0d21d72
Call-ID: 920a7162-7720-48c1-8b71-832fe1de14cf
CSeq: 41309 REGISTER
User-Agent: IP Office 11.1.3.0.0 build 23
Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,NOTIFY,INFO,SUBSCRIBE,REGISTER,PUBLISH
Digest nonce="448f6a34173dd8e20dac",realm="ipoffice",algorithm=MD5
Server: IP Office 11.1.3.0.0 build 23
To: <sip:260@10.25.3.60>;tag=0e6cb8620f2327f2
Content-Length: 0