What are A2P calls?

In this guide, you will be acquainted with what is application to person (A2P) calls.

Imagine this, you picked up a call on your mobile, and someone speaks to you on the other end. The problem is, the other party appears to be a robot. Do you hastily hang up? Or do you find out why a robot is calling you?

Many businesses deploy A2P calling as they do not have the resources to have thousands of employees manually calling their users. This is exactly the reason why A2P calling is so popular. A2P calling basically saves businesses millions of dollars a year, due to its ability to get a message through without requiring humans in the process.

A2P calling typically requires an audio to be played on the call. This could be a nicely craft audio message that was recorded by a professional voice artist, or it could be a slightly machiney voice created from a Text-to-Speech engine. Either way, a voice message rungs out from one end of the phone to another. This technology is enabled by Voice Over Internet Protocol (VoIP), and the specific protocol that Unifonic utilizes is the Session Initiation Protocol (SIP).

When making A2P calling, Unifonic essentially sends a SIP Invite to a SIP provider, who is then connected to the PSTN network. Through the PSTN network, the end user then receives a phone call. Upon answering, the media is transmitted via SIP, and the end result is the audio file being played on the PSTN phone call.

Businesses will interact with Unifonic via Voice APIs, and each Call Request is then handled via SIP Trunks that are connected with trust local vendors. Due to the RTP programmability of each call, businesses are then able to do more than just play an audio file on the call. Businesses will also be able to gather responses from end users with the use of Dial-Tone-Multi-Frequencies (DTMF) or Speech Recognition.

To understand how your business can make use of Unifonic Voice APIs to place a voice call and collect response, please read this guide.