Simplifi celluar communicators ?

Anyone here know if the AT&T Simplifi celluar communicator pot line replacement dialers work with fire panels ?

I have a customer that put one in, but when I use my butte set to call thru the DACT card, it calls my personal phone no problem, but it won’t call the 888 receiver phone numbers to the monitoring stations. I also tried calling a different 800 number thru the DACT and that didn’t work either, but my personal phone called both 800 numbers no problem.

Anyone experience this before ?