Even if you miss this call (which is from the Alarm monitoring company for Monitronics), all you need to do is press the motions button on your alarm to find out which sensor has the low battery. At least that worked for me.

Company is called Monitronics. Alarm Monitoring.

This phone number is from alarm.com which is a home alarm monitoring company. They called me to tell me that my living room had a low signal and I need to replace the battery. I had the alarm guy check it out and he found out that the battery was fine, the motion sensor was faulty and he replaced the sensor.

They either call and leave a message or no message.  And they can't tell you how to get the thing off your door so that you can find out what type of battery you are to buy.  They are not very much help.

Alarm Monitoring Center informing me that my alarm system had a low battery signal. Automated message.