This issue will happen mostly if cellular network will not be down, or suppose if cellular network is down mostly, or it will be rainy or a current cutoff issue might be occurred.
<u>Explanation:</u>
The following step to be made for trouble shoot his phone when cellular network is down.
1. Restart the mobile:- After restarting kindly check mobile connectivity.
2. Check for mobile air plane mobile and make sure the mobile phone is not in air plane mode.
3. Check the income and outgoing vapidity.
4. Switch off the mobile, Remove service provider sim card from mobile and reinsert the sim card and start the mobile.
5. Still connectivity problem, either contact the service provider or replace with new sim card.