Product: Programmable SMS
We noticed that you have tried to add a number to a messaging service associated with a US A2P 10DLC starter campaign. Please note that all starter campaigns have a max limit of 5 phone numbers per campaign. Since you have reached this limit previously, your phone number could not be successfully registered for US A2P 10DLC. If you try to send SMS or MMS messages to the US using this phone number, those messages will be considered as unregistered traffic, where higher fees apply.
You already have 5 phone numbers registered with your starter campaign.
You may continue to send messages to other non-US destinations using this phone number. However, if you want to use this phone number to send to recipients in the US, please consider removing other registered senders from this campaign from the Messaging Services page, or register for a standard A2P brand and campaign instead.