Thank for your reply.

I use webdav. I found the issue. i have nat beetween ctm and exchange. ctm address, 192.168.15.21 is translated in 192.168.150.243. Nat is static.

On the exchange server there are 2 interfaces, one in telepresence vpn and the other, witch is the default, to manage it.

I expected to see the notification with destination address, the translated address ( 192.168.150.243 ), but i found the notification was sent with destination address 192.68.15.21 witch isn't the translated address so the notification left to the wrong interface.

I don't know why this happen ? Is the correct functionnaly ?

My question is how does Exchange know to respond to CTS Manager on udp port 3621?   Udp port 3621 is an Epson port.  Does the subscribe notification during the webdav process tell the Exchange server to notify the user that was created for CTS Manager to connect to Exchange and listen on UDP port 3621 for mailbox notifications?

You are correct . But this is per design. Exchange send Notification to CTS Man on UDP port 3621.
CTS-Manager listening on UDP port 3621

Cisco TelePresence Firewall and Access List Considerations :
http://www.cisco.com/en/US/docs/telepresence/security_solutions/ctss_app_a.html

When the CTSMan server starts, CTSMan will use the CTSMan super user configured on the
Microsoft Exchange in the field "SMTP LHS" to subscribe to all the TP rooms that CTSMan
discovered from the appuser in CUCM.  To "subscribe" to the TP rooms accounts means the
CTSMan super user is allowed to listen on the UDP port 3621 for any event happened to the
TP room account's calendar.

When a TP room is invited by a scheduler in a meeting, the invitation email arrives on the
room mailbox.  When the invite is accepted (either manually by someone login to the room
account, or by auto accept agent), the meeting is placed on the room calendar.  At this
time, the room calendar has a change event happened.  Exchange server will trigger an
event notification on UDP port 3621.  An event will be triggered whenever there is a
change on the room calendars, whether it is meeting creation, meeting modification, or
meeting deletion.

Upon receiving the event on UDP port 3621, CTSMan learns that there is something it needs
to act upon.  Depending on the event type, CTSMan will query Exchange to get necessary
information of the meeting involves the TP rooms account from Exchange and process it
accordingly.

You can get more details from the following link:
http://msdn.microsoft.com/en-us/library/aa142529(EXCHG.65).aspx
http://support.microsoft.com/kb/270836/

Concerning your question : At present, when there is a new meeting, l do a manual synchro and the meeting appear in the ctsm.

[Answer] : If manual synch works successfully [Done via TCP port 80] and automatic doesn't , means UDP port 3621 isn't open between
Exchange server and CTS-Manager.

http://www.cisco.com/en/US/docs/telepresence/cts_manager/1_7/admin/ctm_instalMS.html

Actually it is open.  Here is what seems to be the issue that the firewall cannot nat the ip address of the CTS Manager to a different IP address than what is in the invitation from the CTS Manager or the Exchange server will not have a route to 4.4.4.4 for example.  In this case 4.4.4.4 is the real ip address of the CTS Manager but it has been nat'd to another ip address for example 5.5.5.5 on the firewall.   Because the Exchange Event Subscriber is saying send notifications back to 4.4.4.4 but it's nat'd ip address is 5.5.5.5, the network doesn't know where to send it.  Nothing in the documentation says you can't NAT the CTS Manager.  They actually show examples of the CTS Manager on the other side of a firewall but nothing says you can't have the firewall in between the CTS Manager and the customer's Exchange server with nat'd ip addresses.   I have looked and opened a TAC case too.

18 Nov 2010 18:40:22,189 [GA-EAInternalEventThreadPool-Thread-1] events.ExchangeEventSubscriber - Subscription success for roomSerialId=[1]; roomName=[TPS-140@NorthAmerica.company.com]; callback=[httpu://4.4.4.4:3621/pathTPS-140@NorthAmerica.company.com]; id=[1]; path=[http://10.1.1.3:80/exchange/TPS-140@NorthAmerica.company.com/Calendar80/exchange/TPS-140@NorthAmerica.company.com/Calendar]; displayName=[Telepresence  New Jersey]