Hello everyone,
I am facing a serious issue with my Cisco CP-8851-3PCC phone starting today. The Cisco phone crashes during outgoing calls, but this does not happen with intercom calls or incoming calls.
I had firmware 12.0.3 MPP installed and downgraded to 12.0.2, but that didn't resolve the problem either. I have also performed a reset through the UI and then through the keypad using Hold # on boot and then 123456789*0#, followed by setting up the phone completely anew. However, this also did not lead to any success.
When I initiate an outgoing call, it doesn't connect and crashes after 1-2 seconds.
I can make calls without any issues using the softphone app, so outgoing calls work through that.
I'm really desperate. I have been experiencing this problem since this morning. I noticed some unusual activity. Someone tried to access my 3CX extension, as has happened many times before. The IP originated from Poland and was fortunately blocked. Yesterday, I downloaded and installed an app (Faxbot) that was not properly licensed, from a Russian website. I have already blocked the app in the firewall, but the issue persists.
I have already created a new extension, but the problem persists. Even using the Fritzbox as an SBC (Session Border Controller) without the 3CX SBC doesn't solve the issue either.
I spoke with my SIP provider, and they couldn't identify any unusual IP addresses related to the Faxbot app. Only my ISP's and VPN's IPs were detected. No Polish or Russian IPs were found. I'm sure there are some who might say that downloading a cracked version of an app is not a good idea, but it's a bit too late for that...
I am currently in the process of switching SIP providers, with a number porting scheduled soon. However, it seems to be an issue with the Cisco phone, as the 3CX app is able to make calls.
I have also restarted the Fritz!Box 6850.
3CX Logs:
IP blacklist:
IP: 193.107.216.112
PBX: blocked for too many failed authentications; User-Agent: Cisco Systems
SIP
Activity log:
08/30/2023 17:47:49 - [CM503021]: Call(C:3): ACK is not received from sip:1000@domain.on3cx.de
It seems to me that the Cisco phone might be overwhelmed when trying to make external calls, which is illogical considering it can receive calls just fine. Could it be possible that Cisco has made some changes that could be causing this?
I am ruling out the 3CX system to a certain extent, as the behavior is the same with Fritz!Box VoLTE.
Is it possible that Cisco has blocked my phone? I find it strange that I couldn't select a username for the forum with my existing Cisco account, which is why I created a new Cisco account.
Thank you in advance.
Best regards.
