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How to:
Android: Settings App → About Phone → Status → SIM Status → Signal Strength
iOS: https://lifehacker.com/see-the-actual-signal-strength-on-your-iphone-or-androi-5929546
If the signals are not good,
Move towards a sky-facing area, such as near a window with no obstacles.
Change the current SIM telecom operator with the one that has better coverage in your area
Use a signal booster device
How to go on a Break:
If you would like to go on a break and not receive any further calls, you can enable the associated break while your current call is in progress.
By doing so, your break will be enabled after the call is over, and you’ll not receive any further calls after your current call is over.
After you have come back from your break, you can disable the break and start receiving calls again.