Call a few of your contacts and ask them to call you, as a test. Good reason to say hello to folks with whom you have not talked in a while, too.
Here's the exact wording you should use when texting your friends:
Dear Friend,
Blessings be upon you!
I is hoping all is well with you there in < name of country > .
I need you to try to test me - just as a text!
Warmest greetings,
Your Friend
That should do the trick!
Regards,