From the MPP logs, it was observed that the REFER was accepted but 481 transaction doesn't exists. Reson mentioned as "no resource"
@2021-02-23 01:44:51,881||FINE|SIP|6003|FileName=sip/SIPTCP.cpp,LineNumber=425|RCV sock=77:9 src=10.51.200.72:35835 dst=10.51.169.47:5060 <NOTIFY
sip:10.51.169.47;transport=tcp;asm=5 SIP/2.0
P-Asserted-Identity: <
sip:3906@thecontactcentre.ae>
User-Agent: Avaya CM/R018x.01.0.890.0 AVAYA-SM-8.1.2.0.812039
Via: SIP/2.0/TCP 10.51.200.72;branch=z9hG4bK405394980017550-AP;ft=116
Via: SIP/2.0/TCP 127.0.0.2:15060;rport=35544;ibmsid=local.1601326936885_54012126_54787583;branch=z9hG4bK405394980017550
Via: SIP/2.0/TCP 10.51.200.72;branch=z9hG4bK222405105759412-AP-AP;ft=381;received=10.51.200.72;rport=50369
Via: SIP/2.0/TCP 10.51.200.71;branch=z9hG4bK222405105759412-AP;ft=128
Via: SIP/2.0/TCP 127.0.0.2:15060;rport=23502;ibmsid=local.1601328469179_53133898_53904672;branch=z9hG4bK222405105759412
Via: SIP/2.0/TCP 10.51.200.71:5810;branch=z9hG4bKc6bebe275bb41eb8e60c29bb8650-AP;ft=680366;received=10.51.200.71;rport=49076
Via: SIP/2.0/TCP 10.250.222.15:5810;branch=z9hG4bKc6bebe275bb41eb8e60c29bb8650
Supported: 100rel, join, replaces, sdp-anat, timer
Contact: <
sip:10.250.222.15:5810;transport=tcp;gsid=c44fa460-75bb-11eb-a6b2-000c29905464;asm=5>
Event: refer
Subscription-State: terminated;reason=noresource
Av-Global-Session-ID: c44fa460-75bb-11eb-a6b2-000c29905464
From: <
sip:3906@etisalat.corp.ae>;tag=c451546875bb41eb8d6a0c29bb8650
To: <
sip:69176@etisalat.corp.ae>;tag=c231b26d2974eb15f1c0033a2fa9
Call-ID: fe31b26d2974eb1601c0033a2fa9
Max-Forwards: 64
CSeq: 1 NOTIFY
Content-Type: message/sipfrag
Content-Length: 45
SIP/2.0 481 Call/Transaction Does Not Exist
From
