By submitting a phone number, the phone number will be evaluated for eligibility. Eligibility is determined by what country the number originates from and if there is SMS currently enabled for the number.
If you would like to check the eligibility before submitting the phone number, PastorsLine offers Lookup, a tool to see information about the number. If a number is not of type VoIP or mobile, then the number is eligible to be Hosted for SMS.
VOIP providers that allow us to host SMS with them: