Unable to make calls in Teams from mobile phone

Copper Contributor

Hi everyone, I hope you can help with this rather strange problem.


My organisation uses Teams. It all works perfectly within the organisation and we're able to make/receive calls and send/receive messages. It's also used on company mobile phones via Vodafone's MDM platform.


Everything worked fine up until a week or so ago when we started receiving reports that users weren't able to make/receive calls from within Teams on their mobile phones. It works fine from the desktop (on the network).


So this leads me to believe we have an issue on the MDM. A case has been raised with Vodafone but I wanted to ask whether anyone had experienced such an issue. When I try to make a call from the Teams app on my corporate mobile phone, it rings twice before giving me the following error:


Looks like you're offline

Please connect to the Internet and try again


Bear in mind, the person I'm calling doesn't receive a call and the call also doesn't show in my recent call history log.


When I open the Teams app on my mobile, a Mobile Iron VPN automatically initiates. I've attached the VPN debug file to this post. Could you tell me whether you spot anything in there that may be causing issues? I have question marks over the following lines:


1) MIProxyServer =app-sentry-eversheds-sutherland.vodafone.com

I have asked Vodafone whether they are allowing through necessary URL/ports on this device


2) SentryService = "<TCP_ANY>";

Should there be another entry here for UDP traffic?


3) com.microsoft.skype.teams : (null)

Is (null) correct here?


I hope you can assist me, this is proving to be a real headscratcher!


Many thanks

1 Reply
Does it work if you disconnect or run without the VPN? Running real time communication like Teams over VPN is not recommended, instead you should do split tunnelling so Teams traffic goes outside of the VPN tunnel direct to Teams services.