SMSs or Calls @ iPad

You cannot receive SMSs or phone calls at all to the iPad SIM. You can, however, receive SMSs and phone calls to your iPhone's SIM on your iPad.

See here:

Make and receive calls on your Mac, iPad, or iPod touch - Apple Support

How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac - Apple Support

An iPad is not a telephone but can be used via your iPhone. The sim card is for data plans from your provider and the number is not an actual/real phone number, just a number for them to identify your device.