Why am I missing calls/delayed texts when using mobile hotspot?

[AC Question]

Hardware: Huawei Mediapad x2
Carrier: AT&T

Problem: missing most calls while using mobile hotspot, and messages are getting delayed (if I turn the hotspot off, cycle on/off airplane mode they come in within a few minutes

Any ideas what could be the issue?

 

[tony bag o donuts]

Does your phone support simultaneous calling and data? If so, is it turned off in the device settings? If you are in a weak signal area it may not support it.

For instance, Verizon now has Advanced calling. If this is turned off, calls cannot be placed when data is used and if using data, voice is disabled (at least on my device).