All phone carriers participate in an international database that contains every phone number currently in use. The phone carriers will report what type each of those numbers are: mobile, landline, or VOIP (VOIP = Voice over Internet Protocol or when you used your internet connection for phone calls). When you upload your CSV, ThruText will compare every number in that CSV and report on what type of number each phone number uploaded is. If it is texatable, we will mark it as valid and if it isn't we will mark it as invalid.
If you want to verify your group info, you can export out your group from the group page. You can see in the exported CSV what is or is not a valid number. Here is an example:
You can also see an overview in the Group page view:
Once your Group has been validated, you can then create your campaign.
Note: In ThruText, you can only text mobile numbers. This might cause confusion with VOIP numbers that do offer the ability to send and receive texts (such as Google Voice). While those carriers do exist, the large majority of VOIP numbers are in use to replace landline numbers and do not accept SMS. To keep deliverability high and save your costs for undelivered messages, we don't allow texting of VOIP numbers.