There are only a few reasons why Sim won’t work , Traditionally speaking nothing is perfect.
Our Tier 1 Global Data sim is almost perfect but there can be many factors that involve a sim connection.

1. You are out of data – Please make sure customers always set their data limits.
2. Its not activated
3. APN wrong
4. Shitty area signal if you are in the mountains , you are directly under the sun…….. now !
5. User is challenged
6. User changed settings or is still challenged !

if none of these 6 , then will will always work

Oh and least case :

1.Carrier is down in the area or globally 2-3% that can happen per year 95-98% uptime
2.Phone antena broken
3.Sim card damaged
4.Weather and or damaged towers

Don’t Skimp out on your provider or trusted business consultant because we don’t want you to come back until its time to renew 🙂