Cannot hear each other on phone call randomly.

I have a Xiaomi Redmi Note 11 not note 11 pro!!. I have been getting problems during phone calls. There are sudden disruptions where neither of us can hear each other. The speaker seems fine as I use it ,also the mic is fine as I can WhatsApp call. But there are problems only with phone calls through sim. The sim also seems fine to me as my data works very good. The calls sometimes have no problems but sometimes have slightly long disruptions .