Airtel Sim — Airtel sim not registering network

Hi, I am staying in Dubai and keeping the airtel number
This number is with me now more than 14 years and all my services are connected to this.
Every month I keep on recharging to keep the sim active, last few days I noticed it is showing NO SERVICE, in my Airtel application it is active.

Kindly resolve this issue at the earliest as am facing some issues because of this.