Technology: Will you send the variable through a SIP or an IAX channel ?
Header prefix (for SIP): You can (partially) choose the name of the SIP header to be sent. The header's name will have the form X-<value of this field>-<name of the variable>. If you leave this field empty, the header will be named X-<the name of the variable>.
Variables: the list of variables you want to send.
Example of use
For SIP:
Set the variable with this action, with the Technology parameter set to "SIP".
The header will be named X-<the name of the variable> by default, or X-<value of the Header prefix field >-<name of the variable> if you have entered something.
You can fetch the variable's value on the other host by using a SetVar. In the "Value" field, enter something like ${SIP_HEADER(<the entire header name>)}. For example ${SIP_HEADER(X-foo)} if your variable is named "foo" and you leave the Header prefix parameter empty.
For IAX:
Set the variable with this action, with the Technology parameter set to "IAX".
The variable sent will have the same name.
You can fetch the variable's value on the other host by using a SetVar. In the "Value" field, enter something like ${IAXVAR(foo)} if the variable sent is named "foo".