Can't chat in Microsoft Teams on Android with coworker with internal phone number 911

Premise: I'm living and working in Switzerland where 911 isn't an emergency call number. One of my colleagues has an internal phone nr 911 (which can't be changed easily because it's mapped directly to the last three digits of the external phone number) Communicating with him in Teams works without any special issues in Teams on Windows. Trying to chat with him in Teams on my mobile phone fails because Microsoft feels compelled to warn me that I can't message 911 via Teams. I looked for an option to skip this Message but I'm only presented with the option to call 911 or send an SMS to 911 (which makes sense in about a dozen countries in the world). A quick Google search didn't turn up anything useful for me. Can you explain to me how to get the chat with my colleague working or point me to a resource that explains how to solve that problem? **Update:** It's even weirder! The user has the internal Phone number 988 and not 911. Now I'm totally confused! With other coworkers whose internal phone number starts with 9 I can chat without any issue...