Why is my facebook messenger app not receiving calls?

[Android Central Question]

First of all this is happening on an iPhone but I thought maybe the platform is irrelevant for this issue

So when someone tries to free call me on messenger, it appears to the person trying to call me as if I'm offline (active since..) although I'm connected to the internet and have good internet connection... so it says "contacting.." and stays like this until it disconnects and asks them to leave a message.. after they end the call I immediately receive a notification saying that this person tried to call me (which kinda proves I'm connected)

Also if they try to send a message it only says sent (not delivered)

That being said.. when I unlock my phone and open the messenger app, this problem no longer exists ..I appear online and people can call..

Anyone?

 

[Josiah Eleazar Regencia]

Hi. I'm having the same problem. Messenger calls not working. How did you fix this? Although I'm on an Android