Saldo de tarjetas de crédito por teléfono

Queremos que monten un asterisk, para poder usarlo para que cuando un cliente llame, pueda ingresar número de tarjeta de crédito, contraseña y entonces le de el saldo.

Tengo entendido que puede operar bajo la siguiente función:

CURL()
Synopsis
Retrieve content from a remote web or ftp server
Description
When this function is read, a HTTP GET (by default) will be used to retrieve the contents of the provided url. The contents are returned as the result of the function.
Example: Displaying contents of a page
1 exten => s,1,Verbose(0, ${CURL(http://localhost:8088/static/astman.css)})

When this function is written to, a HTTP GET will be used to retrieve the contents of the provided url. The value written to the function specifies the destination file of the cURL'd resource.
Example: Retrieving a file
1 exten => s,1,Set(CURL(http://localhost:8088/static/astman.css)=/var/spool/asterisk/tmp/astman.css))

Note
Icon
If live_dangerously in asterisk.conf is set to no, this function can only be written to from the dialplan, and not directly from external protocols. Read operations are unaffected.
Syntax
CURL(url,post-data)
Arguments
1. url - The full URL for the resource to retrieve.
2. post-data - Read Only
If specified, an HTTP POST will be performed with the content of post-data, instead of an HTTP GET (default).
See Also
1. Asterisk 16 Function_CURLOPT