On CUCM side, you set "MTP required" for the SIP trunk. The trunk should terminate on port 5080 on FreeSWITCH server (5060 requires authentication).
On FreeSWITCH side, a standard <gateway> needs to be configured to be able to send calls to CUCM. The calls from CUCM will land in "public" profile.
Feel free to contact me privately, I can speak Russian :)
From: Nick Zaitsev
<nick.zaitsev@mail.ru>
To: freeswitch-users@lists.freeswitch.org
Sent: Tuesday, August 13, 2013 10:55 AM
Subject: [Freeswitch-users] freeswitch trunk cisco call manager