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: