Why can't I hear the dial ringing when calling my mom?

[Android Central Question]

Hi.

I have a ZTE Blade Z Max with Metro PCS. I sent my mom a message and then decided to call her but I couldn't hear the ringing. I think her phone is dead because I haven't gotten a text back either. I decided to call my sister's phone and I could hear the ringing. Called my mom's phone again and no ringing. The first time I called her, it sounded like she picked up but then I got a voicemail. Did she get my calls? Is there anything I can about this?

Thanks

 

[B. Diddy]

Welcome to Android Central! Is there any other way you can reach her right now? As your sister to call her -- does she get the same result?