A Twilio Messaging Service can contain up to 400 long code numbers by default, regardless of country.

If you reach this limit and try to add additional senders to your Messaging Service via API request, you will receive an Error 21714 response.

Requesting to increase sender pool limit for a Messaging Service

If you need more than 400 numbers in a single Messaging Service, please contact Twilio Support about a Messaging Service sender pool limit increase.

If you reach out to request a sender pool limit increase, be sure to include:

• Your Twilio Account SID
• The Messaging Service SID you are requesting the increase for 
• How many senders you wish to have in your Messaging Service (your requested limit)
• A description of your messaging use case and why you need a higher sender limit