Getting a lot of "No Service"

iPhone 6 has been displaying "No Service" an awful lot since I've had it. At work on my last phone would always have at least 2 bars of signal and has never ever dropped signal completely.

My iPhone 6 does display 2 bars at work so I know the signal strength here is OK but only for about 50% of the time, the rest of the time it just says "No Service". I can usually get the signal back by toggling Aeroplane mode but that doesn't always work.

Any fix for this?

 

Carrier is fine, my other Samsung phone on the exact same plan has perfect signal and never ever shows no service. I think the iPhone is just clearly not as good at receiving signal.