Your gCast account comes with the ability to send SMSs and be billed by gCast/Gen3Media for those SMSs.
The default setting for this to work is to have the gCast option selected on the SMS integrations page.
However, if you have user credentials with a provider of your own, you can choose from the available providers and enter in your credentials to be billed by your provider, not by gCast.
If you can't see your provider in our list, please contact Support for more assistance.
Don't forget, your credentials must be correct and all fields completed if you choose your own provider, otherwise your SMS campaigns will not send.