This article discusses whether the M50/M50C is capable of making phone calls

The answer is NO. The Cellular option is an alternative means for accessing WiFi capabilities, not for making regular calls. There is no dial pad on the M50. The only option for making phone calls is installing 3rd party apps such as Skype, Line, WeChat, etc.

The below information is from the M50/M50C Users Manual

About Cellular Phone - (LTE/4G/3G) (M50C WWAN SKU only)

The cellular phone is limited to a 3rd party calling (Skype, Line, WeChat). No voice calls.
The following bands supported on AT&T, Verizon, T-Mobile, and Vodafone networks.

• Supported Carriers Bands