Softphone & SMS API terms, defined.
Clear, developer-grade definitions for the voice and messaging concepts behind a programmable phone system. Each term links to a short page with an example and how it maps to VanceTel.
Eight terms worth getting right.
Softphone
What is a softphone?
A software phone that makes and receives calls and texts on a computer, tablet or mobile device over the internet — no desk handset required.
Read the definitionCPaaS
What is CPaaS?
Communications Platform as a Service: cloud APIs that let developers add voice, SMS and messaging to their own apps without running telecom infrastructure.
Read the definitionA2P 10DLC
What is A2P 10DLC?
The US carrier framework for sending application-to-person SMS from a standard 10-digit long code, gated by brand and campaign registration.
Read the definitionE.164
What is E.164 phone number format?
The international standard that writes a phone number as a plus sign, country code and subscriber number, up to 15 digits — for example +15551234567.
Read the definitionMCP server
What is an MCP server?
A Model Context Protocol server that exposes tools and data to AI agents over a standard interface, so a model can take real actions in the loop.
Read the definitionTwo-way SMS
What is two-way SMS?
Text messaging where a business number can both send and receive — recipients reply, and those replies thread back into the same conversation.
Read the definitionClick-to-call
What is click-to-call?
A link or button that launches a phone call to a specific number the moment it is clicked, with no manual dialing.
Read the definitionHMAC webhook verification
What is HMAC webhook verification?
A way to prove a webhook is genuine by signing each payload with a shared secret, so the receiver can confirm the sender and that nothing was altered.
Read the definitionFrom definitions to a working phone system.
See the softphone, the REST API and the website-chat-to-SMS flow in a short walkthrough.