Cisco 7960 Registration issue

[Telex]

Hello everyone,

I have some Cisco 7960 phones.I did manual configuration was working fine till yesterday.
There was a power bump & phone lost the registration & never got it back.
I checked in sngrep,
Here is the data for the registration, phone sends the request but not getting to authentication.

2021/07/04 21:09:49.677835 xxx.xxx.xxx.xxx(Source IP):1026 -> xxx.xxx.xxx.xxx(Destination IP or Server IP):5060
REGISTER sip:mydomain.com SIP/2.0
Via: SIP/2.0/UDP xxx.xxx.xxx.xx:5060;branch=A9hG4bS4b86d370
From: <sip:EXT@mydomain.com>;tag=081980c8d19301430fa72f56-18e616d0
To: sip:EXT@mydomain.com
Call-ID: 001930c8-d1931005-43011257-7674d67f@xxx.xxx.xxx.xxx(Source IP)
Max-Forwards: 70
Date: Mon, 05 Jul 2021 03:09:49 GMT
CSeq: 112 REGISTER
User-Agent: Cisco-CP7960G/8.0
Contact: <sip:EXT@xxx.xxx.xxx.xxx(Source IP):5060;transport=udp>;+sip.instance="<urn:uuid:00000000-0000-0000-0000-001830c7d193>";+u.sip!model.ccm.cisco.com="7"
Content-Length: 0
Expires: 180

Any solution Please, Phone does not go to authentication process.
Not sure from where it's taking port 1026 with source IP indicating

 

[hfoster]

You still have rport enabled?

 

[Telex]

Thanks for your response, Switch is on default config nothing changed with regards to rport.It was working on 180 sec register request for last two months,not sure what changed after power outage.Switch is not behind NAT,Phones are.

 

[hfoster]

rport is on the phone, not the networking equipment. It's to tell the phone to use arbitrary ephemeral return ports. Might also be some SIP ALG nonsense on the router in front of the phones perhaps.

 

[Telex]

SIP ALG is disabled on the router.Randomly one phone registers & loses it's registration after couple days.

 

[Telex]

I am unable to find rport settings on these devices.It does not support GUI,converted from Skinny to SIP,I checked SIP & Network settings both.