Application-to-Person messaging (A2P) is one-way SMS to which recipients are not expected to reply. When you send a text message to vote for your favorite singer on the TV talent show, you are using A2P messaging. Software applications use an API to send an receive texts.
Wireless carriers treat P2P and A2P traffic differently in terms of the type and volume of traffic allowed. To avoid carrier filtering it is important to understand your use case so you can use the correct tools such as phone numbers, short codes, and routing intelligence.
Learn more about the difference between A2P and P2P SMS.