Default Can't receive texts after upgrade?

Hi guys so I just got an LG g3 and I gave my old phone (HTC one m7) to my mom so she was upgraded from an atrix 4g to my m7. I'm on at&t btw.

My g3 is working fine, her m7 isn't able to receive texts. She can make and receive calls, she can send texts out fine, but she can't receive texts. Data is working fine.

I've checked everything, imei is there, apn settings are correct. Any idea what it could be? I'm planning to take it to a store tmrw, after I do a factory reset.

Any idea what it could be?