3cx Android, no more ringing if a call arrives

[Hans Marc]

Hi,

we have a strange problem since this morning.
When the office call a mobile android phone, the phone is no more ringing, there is no notification.
We see in the list of all extensions that a call arrives because it is blinking red.
We checked 3cx settings on the mobile and we can confirm that it is not in silent mode.
Reboot mobile phone, the problem is still there.
All company mobile phones have the same problem.
It is thus not related to only one phone.

The mobile phone can launch a call to a internal extension or a mobile external number.

All update are installed on the server V20 (patch7) and we did a reboot of the server.
Mobile phones version is 5.4 build 55, 20.5.0.55.

Regards
Hans

 

[bitn2]

This could be related to an network problem. Are the phones connected bey wlan or lte?

 

[NikosT_3CX]

@Hans Marc the mobile devices are on the same network or not ?
I mean are all on Wifi or you also have the same issue on 5G?
It would worth putting the PBX in Verbose mode, make some test calls, download the support info and then
check the System Service log.
Do you see any exceptions there ? Or on the Event Logs on the Dashboard ?
Do you have 8.8.8.8 as the primary DNS set on the PBX side ?

 

[Hans Marc]

Hi Nikos,

All mobile phones are outside thus connected via a home wifi for home workers and 4g for people on the road.
All services are running.
Below a event log dump.


Regards
Hans

rror	50020	01/23/2026 12:56 PM	System Manager	DEFAULT	Failed to send FCM PUSH to device samsung SM-G970F(Ext.42). Internal exception occured: System.Exception: ERP didn't provide a token. Error code: NotFound. at _3CX.Push.PushTransport.GetFcmToken(). at _3CX.Push.PushTransport.PushAndroidFcmV1(PushTask pushTask). at _3CX.Push.PushTransport.PushAndroidFcm(PushTask pushTask)
Error	50020	01/23/2026 12:54 PM	System Manager	DEFAULT	Failed to send FCM PUSH to device samsung SM-G970F(Ext.42). Internal exception occured: System.Exception: ERP didn't provide a token. Error code: NotFound. at _3CX.Push.PushTransport.GetFcmToken(). at _3CX.Push.PushTransport.PushAndroidFcmV1(PushTask pushTask). at _3CX.Push.PushTransport.PushAndroidFcm(PushTask pushTask)
Error	50020	01/23/2026 12:53 PM	System Manager	DEFAULT	Failed to send FCM PUSH to device Xiaomi Redmi Note 9 Pro(Ext.14). Internal exception occured: System.Exception: ERP didn't provide a token. Error code: NotFound. at _3CX.Push.PushTransport.GetFcmToken(). at _3CX.Push.PushTransport.PushAndroidFcmV1(PushTask pushTask). at _3CX.Push.PushTransport.PushAndroidFcm(PushTask pushTask)
Error	50020	01/23/2026 12:53 PM	System Manager	DEFAULT	Failed to send FCM PUSH to device Xiaomi Redmi Note 9 Pro(Ext.14). Internal exception occured: System.Exception: ERP didn't provide a token. Error code: NotFound. at _3CX.Push.PushTransport.GetFcmToken(). at _3CX.Push.PushTransport.PushAndroidFcmV1(PushTask pushTask). at _3CX.Push.PushTransport.PushAndroidFcm(PushTask pushTask)
Error	50020	01/23/2026 12:07 PM	System Manager	DEFAULT	Failed to send FCM PUSH to device samsung SM-G970F(Ext.42). Internal exception occured: System.Exception: ERP didn't provide a token. Error code: NotFound. at _3CX.Push.PushTransport.GetFcmToken(). at _3CX.Push.PushTransport.PushAndroidFcmV1(PushTask pushTask). at _3CX.Push.PushTransport.PushAndroidFcm(PushTask pushTask)

 

[Hans Marc]

Hi Nikos,

below a full dump of one of the errors

Severity	Error
Event ID	50020
Date	01/23/2026 12:56 PM
Details	Failed to send FCM PUSH to device samsung SM-G970F(Ext.42). Internal exception occured: System.Exception: ERP didn't provide a token. Error code: NotFound. at _3CX.Push.PushTransport.GetFcmToken(). at _3CX.Push.PushTransport.PushAndroidFcmV1(PushTask pushTask). at _3CX.Push.PushTransport.PushAndroidFcm(PushTask pushTask)

 

[NikosT_3CX]

@Hans Marc where do you host this PBX ?
Is the license activated ? Refresh once the license.
Does the machine have access on the below FQDN ?
Check our guide what is required for the PBX :

https://www.3cx.com/docs/manual/firewall-router-configuration/#h.8pfa34ntckn1

• Push Service (Android & iOS)

pbxservicespush.3cx.com, 443 (outbound, TCP, uninspected traffic)