We are not receiving text messages from monitors that are down since roughly in the middle of this week. There are a couple getting through but not to all contacts.
Release : 10.1
Component : CA APP SYNTHETIC MONITOR (WATCHMOUSE)
Per Engineering, the issue seems to be related to SMS vendor.
Try using different SMS/texting provider as the image below.
You could try one at a time , m1, bu, m2...etc