I urge you to search the mailing list archives of FreeSWITCH. More than ten year of daily technical discourse about how to do things in and with FreeSWITCH. They are plenty of incredibly deep and accurate information that has been written by the brightest people discussing and solving problems. Not only you learn the answer to your question, the "how-to", but also you'll be able to follow the line of reasoning conducive to that.

Yay for the mailing list archives: http://lists.freeswitch.org/pipermail/freeswitch-users/