Microsoft Teams calling issues

[itresearcher007]

Hello everyone,

We are using Microsoft Teams (Personal version) for calling and since a few weeks we are facing issues in calling each other. When we try to call the other users through one-one, i.e., the audio calling option most of the times the calls doesn’t get placed even if the recipient has been added as a contact in the Teams app and messages/chat interaction have been done before between them.

1. In some cases, when user “A” tries to call the user “B” the audio calling option itself will be greyed out when both of them are online, but for the user “C” the call option for user “A” will be displayed as enabled and he/she can call “A” successfully without any problems. This occurs in Teams desktop for windows and also on the Teams web and Android application. (as shown below)

2. In other cases, the users will not be able to call the recipient even when both of them are online. As per few searches online got to know issue maybe linked to their Status ( a.k.a presence) but we tried resetting the status and issue still repeats.

3. A few other issues, where the call would ring and then display to the caller that the other user is ‘Unavailable’ even when presence is online and the recipient is connected to Teams app.
   

   

These issues are occurring intermittently and at random.

What we’ve tried so far:

Checked the Teams settings
Reinstalled MS teams and made sure its latest versions
Deleted the Teams application cache, local packages
Network connections and internet speed & bandwidth
Audio settings, sound drivers of the users computers

Specifications:

MS Teams versions: 25163.3611.xxxx (updates are on)
OS: Windows 10 and 11
Antivirus: SentinelOne Singularity control in most of the computers
Internet speed: Over 300-500 Mbps most of the time (as per www.fast.com )
Sound driver: Realtek audio

These issues were not present in Skype and have started recently after we began using MS Teams.

We have tried searching online for solutions and most of the web links point out to internal Teams setting or call options such as Call forwarding, routing etc., as mentioned here and here, which are not present in our version as use the Microsoft Teams Free (personal) application.

Any advice or help in resolving is appreciated!

[Christopher-Collings]

I can understand how that would be really frustrating @itresearcher007.

Thanks for all the details! Quick question to narrow this down: are both users signed in exclusively with Teams Personal accounts, or is one of them on a Teams Business (work/school)? Mixing personal and business accounts can sometimes disable the call button.

[itresearcher007]

Thanks for your response. Both (and all of us) users are using Teams Personal users. We do not have Teams Business or licensed plan users among us.

[itresearcher007]

EDIT 21.7.2025 : We are behind a Fortinet firewall. (However we don’t think that would be responsible, as some users are not able to place a Teams call to a few particular users even from their Android mobile app on the mobile data network)