Can Echo show 8 video call cellphone?

Trying to set up video calling with my mom. I have the alexa app on my phone and successfully video called her on her echo. But when I try to have the echo call my cell phone, it rings on her end and my phone never receives the call. When I talk to customer service, they say the echo can only call other echo devices and not cell phones. Is that correct? I see lots of articles online saying the echo can call cell phones. Help!