If you have a phone number but do not know the service provider for the SIM, you can find it out. 

 

Here is how to check a SIM card company by Mobile Number:

If you have the SIM inserted in your phone, then it is feasible to check the network provider details via the phone settings.

 

●  For iOS Phones:

1. Go to Mobile Settings and navigate to General
2. Click on About and Scroll down to Primary/Secondary
3. Under Network you will see the Primary/Secondary Network Provider Name

●  For Android Phones:

1. Open the Mobile Settings App
2. Click on Network and Internet and Tap on Cellular Networks
3. From available networks you can know the SIM card company
4. The process might vary depending on the device type, but is more or less the same.