In case your customer had an account with Twilio before, and they want to keep using the same account with you, their Twilio account will need to be moved into your agency's Twilio.
In order for Twilio Rebilling to work, your customer's sub-account in HighLevel needs to be connected to a corresponding sub-account in your Twilio account.
If your client's sub-account in HighLevel is currently connected to a Twilio account of their own, you'll need to follow the following steps before activating Twilio Rebilling in SaaS mode:
Step 1 - Log into your Twilio account > click the Gear Icon > select sub-accounts > click the red + icon to create a new sub-account and name it to match the client you want to activate Twilio Rebilling for
Step 2 - Copy the text template below and add in the missing info
My client [client name] whose Twilio account is registered under [client's Twilio account email] would like to move the following numbers from their account to a sub-account in my account:
[list of phone numbers]
The Losing Account SID is: [the SID of the sub-account that is giving up the phone number (you can find this in your HighLevel account > Agency Settings > Twilio tab next to your client's name in the list)]
The Gaining Account SID is: [the SID for the new sub-account that you created in Step 1]
We would like the number(s) above transferred as soon as possible. Thanks in advance!
Step 3 - Open a support ticket from within your Twilio account by clicking the question mark icon and selecting "Submit a Ticket". Paste the completed text from the template above into the ticket and submit.
Step 4 - Change the first paragraph of the text template to read "I would like to transfer the following number(s) from my Twilio account to another account:" > send the updated text template to your client and request that they open a ticket from within their Twilio account using the text template. Twilio will need tickets from both you and your client in order to approve the transfer.
Step 5 - Once you receive confirmation from Twilio that the transfer has been completed, you should see the number(s) in the new sub-account you created in your Twilio account.
Step 6 - Log into your HighLevel account > go to Agency Settings > Twilio > scroll down to your client > click the three dots icon to the right of their account name > select "Update Credentials" and replace the SID and Auth Token values with the new SID and Token values from the new sub-account in your Twilio account.
You can obtain the new SID and Token by logging into your Twilio account > click the gear icon at the top right > select Sub-accounts > Click the name of your client and you will see those two fields: