Good news!
We’ve simplified A2P (Application-to-Person) requirements to make messaging across the United States and Canda more consistent, reliable, and compliant — all while keeping things easy for you.
OVERVIEW
This guide explains the messaging requirements and error codes related to A2P (Application-to-Person) registration and Persona verification for both domestic and international routes. Understanding these rules helps ensure that messages are delivered successfully and that compliance issues are avoided.
Domestic Messaging (Within the US and Canada)
When sending messages within the United States, Canada, or Puerto Rico, A2P (Application-to-Person) registration is mandatory.
What This Means
Any messages sent between domestic numbers—such as US → US, US → CA, or CA → US/PR—must originate from a registered A2P number. This requirement ensures compliance with carrier regulations aimed at preventing spam and unauthorized messaging.
If A2P Registration Is Missing
Messages sent without A2P registration will fail and return the following error:
Error 30034 – Number not A2P compliant. Please register for A2P.
Example Scenarios
A message from a U.S. business number to a U.S. customer → A2P required
A message from a U.S. number to a Canadian number (or vice versa) → A2P required
Rule for CA → CA Messaging
For Numbers PurchasedBefore March 26, 2025
A2P registration not required
Messaging continues as usual
For Numbers PurchasedOn or After March 26, 2025
Messages can be sent with or without A2P registration
If A2P registration is not completed, you only need to complete persona verification.
In summary:
All domestic messaging routes require an approved A2P registration for proper delivery—except for CA → CA, where older numbers are exempt and new numbers require either A2P registration or Persona verification.
International Messaging (From US or Canada to Other Countries)
For messages sent from the US or Canada to international destinations, A2P registration is not required. Just Persona verification is needed for these messages to be delivered successfully.
What This Means:
International messaging relies on the sender’s verified identity rather than A2P registration. Persona verification confirms that the sender’s details have been authenticated and approved.
Message Behavior:
If the sender’s persona is verified, the message will be delivered normally. A2p verification would not be required in this case.
However if there is no A2P registration and no persona verification, the system will block the message and return the following error:
Error 1002 – Message blocked. A2P or persona verification needed.
Example Scenarios:
Sending from a US number to a customer in France → Allowed (Just Persona verification required)
Sending from a Canadian number to a customer in Australia → Allowed (Just Persona verification required)
Sending without persona verification → Blocked with Error 1002
Essentially, international messages from US/CA numbers only require Persona verification, not A2P.
Exception: Messaging to the United Kingdom (UK)
The UK is a special case in international routing rules.
Messages from the US to the UK are not allowed and will fail automatically.
The system returns the following error when this route is attempted:
Error 21612 –Message cannot be sent with the current combination of "To" and/or "From" parameters.
However, UK-to-UK messaging is permitted.
Key Takeaways
Domestic (US/CA/PR): Always requires A2P registration.
International (US/CA → Other Countries): Requires Persona verification only.
No A2P or Persona: Results in blocked messages with Error US → UK: Not supported; Error 21612 returned.