Delay in push notification on message and calls

Dear Team,
There is very much delay on receiving push notification messages.

After a message or calls done from one device, the other device receives the message or call after 20 to 30 min.

This looks very odd on audio and video call. Because once a call made and rings until ‘unanswered’, no notification received or the user receives the call on notification after very long time.

Why such delay? I want to receive immediately once call made kindly look on it. Reply how to handle this?

Dear Team,
Waiting for the reply.

Dear Team,

Still no reply waiting for the response