No it's not Microsoft. Welcome to the internet. It's probably someone on Azure trying to find vulnerable systems. Have a look at some of the Videos from Astricon explaining the pitfalls of voip fraud and security.

https://www.youtube.com/watch?v=9Wzzlo1kfTQ (disclaimer: that's my talk)

https://www.youtube.com/watch?v=CCDqpJc2aXQ
https://www.youtube.com/watch?v=h5Fw70KzAls
https://www.youtube.com/watch?v=hLFz8mlmKIY

On Tue, Nov 3, 2020 at 2:55 PM Max Tulyev <maxtul@netassist.ua> wrote:

Hi All,

I have just seen a number of IPs trying to brute-force my VoIP server
from Microsoft network. For example, 13.90.148.133, 20.55.203.249,
40.76.244.210... Traceroute really goes to MSN. More than a half of all
usual attempts to hack my Asterisk I got today, came from MSN.

What is happening? Am I missed something?