If SMS Validation has been activated, we will check Twilio Lookup (charges per lookup) to see if the number is a landline and won't send any messages to it.
Twilio Lookup also invalidates numbers that are badly formatted or don't exist.
Validation is only done on SMS sending, not on Contact Import/Creation.
Validation only needs to be activated in HighLevel to function (it is on by default in Twilio).
How to enable SMS / Phone number Validation?
Go to Agency Settings -> Twilio -> A new column called SMS Validation
*PLEASE NOTE that phone number validation is a paid service from Twilio. You can view pricing for "Carrier Lookup" here.