Why is my phone making random phone calls?

[motf]

My phone is making random calls while in sleep mode.

[vzw_customer_support]

This is a mystery to us too, motf! When did this issue start? Which make/model phone do you have?

LasinaH_VZW
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[motf]

It started last week.  It's HTC 526

[demmo86rt]

You sure you aren't waking it up in your pocket?  I like to keep a secure lockscreen on my devices just to prevent this.