Restcomm allows to programmatically send and receive SMS globally through simple RESTful APIs or a powerful drag and drop Visual Designer.

  • Programmatically send and receive high volume of SMS.

  • Build apps that scale with the web technologies that you are already using.

  • Restcomm enables you to stay in control of SMS delivery, speed and quality in allowing you to bring your own carrier to Restcomm.

  • Restcomm can put your existing numbers to work or enhance your Unified Communications Client by SMS Enabling them on Restcomm through Message Exchange.

API Reference

Base URL

All URLs referenced in the documentation have the following base:

The Restcomm RESTful APIs are served over HTTPS. To ensure data privacy, unencrypted HTTP is not supported.



RCML is a set of instructions you can use to tell Restcomm what to do when you receive an incoming call or SMS.

When someone sends an SMS to one of your Restcomm numbers, Restcomm will look up the URL associated with that phone number and make a request to that URL. Restcomm will read RCML instructions at that URL to determine what to do: perhaps respond with a message or transfer control of a message response to a different URL

RCML is similar to HTML. Only one RCML document is rendered to the caller at once, but many documents can be linked together to build complex interactive SMS applications.

Restcomm’s request to your application

Restcomm makes HTTP requests to your application just like a regular web browser, in the format application/x-www-form-urlencoded. By including parameters and values in its requests, Restcomm sends data to your application that you can act upon before responding.

You can configure the URLs and HTTP Methods Restcomm uses to make its requests via your account portal or using the REST API.

When Restcomm receives a message for one of your Restcomm numbers, it makes a synchronous HTTP request to the message URL configured for that number and expects to receive RCML in response.

Restcomm sends the following parameters with its request as POST parameters or URL query parameters, depending on which HTTP method you’ve configured:

Request Parameters

Parameter Description


The unique identifier for this message. May be used to later retrieve this message from the REST API.


The id of the Account this message is associated with.


The phone number that sent this message


The phone number of the recipient.


The text body of the message.

The RCML verbs for Programmable SMS

Restcomm Response

In your response to the request from RestComm you want to provide RCML that will instruct RestComm on how to handle the current call.

MIME Types. RestComm supports the MIME types described in the table below.

Supported MIME Types

Parameter Description

text/xml, application/xml

RestComm interprets the returned document as an XML instruction set.

When your application returns the RCML document the root element of the document must always be <Response> or the parser will complain.