Receiving Calls on Android not ringing

The fleet of Android phones we are using are all locked down using the Managed Home Screen app (Android Enterprise multi-app kiosk mode).  We discovered that the Managed Home Screen app must be set to 'Unrestricted' battery, in addition to Teams itself.  This eliminated ~90% of the issues with our phones not ringing when called.

An underlying issue still remains though, despite all battery/power saving options being disabled for the relevant apps.

Microsoft have acknowledged that there was a bug preventing Teams from ringing when used with Managed Home Screen in early 2023.  After providing them with bug reports they have commented that they believe the bug still exists and have asked for additional bug reports from our phones.

robnicholsonmalt  That's a really good shout, but unfortunately the user the calls comes into from pstn, is a standard user setup on  desktop phone. So we don't see that setting, if it even exists for standard users .... We only really need it to ring on the two devices simultaneously, but it may be related to presence I'm guessing 

alig69 turning off presence-based routing worked for my two clients using Teams as the main number.

Did anyone ever get to the bottom of this, any fixes? Just migrated my organisation to Teams voice, and this same issue has started to occur on some of the Samsung A23 phones we are using. Its worrying, as we use the Samsung mobiles as the walkabout phones, and confidence has been dented, as they are intermittently not ringing. The calls to our main number are supposed to simultaneously call the mobile Teams account. This worked very well in testing, but it seems the phone goes into some sort of sleep. It works again if you call the mobile account directly via Teams.

This seems to be a common problem and is darn annoying as it prevents you using a mobile phone as a cheap reception handset. I've been helping a charity set-up a Teams call queue which rings two users/mobiles at once. They report that the phones don't ring and it goes straight to voicemail. 

I'm currently testing it with Teams app on PC and on another mobile. If the screen is off (locked), then it rings on the PC immediately but can take 5-10 seconds to wake up the mobile. At which point it reaches time out and flips to voicemail. The phone I'm testing with is old. Will try with their brand new Xiaomi phones in the office after the bank holiday weekend.

Peter_De_Bruyne_STZH 

Thanks for your reply!

How about Android 13? No issues for you there?

The settings you describe are also available in Android 13, but through a slightly different route. There were 7 apps even with 'wifi' in its name. I put them all to 'Unlimited' for battery optimisation. Now wait and see if it has effect...

PS: we also experience the issue on 4G. So I doubt this will be a full fix. But any improvement is welcome.

And would love to hear the outcome of the new firmware test next week (or later..)!

We have exactly the same experience on our Xcover 4 (SM-G398FN - android 11) and 5 (SM-G525F - android 11) as well as on our Xcover Pro (SM-G715FN - android 12). We have also disabled any possible setting regarding battery optimisation on Teams and Wifi ! For WIFI, we disabled battery optimisation by excluding 3 background WIFI services from battery optimisation. The latter reduces the frequency substantially on missed calls after some idle time. It does not completely eliminate the problem however.

One can do this via Apps -->Special Access (via 3 dots) --> battery usage optimisation --> select ALL apps --> filter on "wifi" and you will see 3 android system services: disable battery optimisation for all 3

As this does limit the missed calls while not seeing nor hearing them, occassionally the problem occurs again.

Samsung is aware about this problem and the root-cause is the combination of the WIFI chipset and the supporting firmware. They are currently testing an improved firmware for which we hop to see succesfull testing next week.