We have about to move all our blackberry devices from 1 bes to another.

The old bes server is run by another part of the company and I don't have any access to the bes and politics make getting work on it done difficult.

If a device that was connected to the old bes, is security wipe can it then go through the enterprise activation for the new bes or will it still continue to try and comunicate with the old bes server until it is removed. If this is the case is there anyway around getting the device onto the new bes before it is removed from the old bes server.

Please someone say yes

Do a security wipe of the device(s) before activation on another BES server...that should always be your Best Practice approach. A security wipe removes the data(former BES service books..etc) and previous encryption keys that once pointed to the old BES.
I'll assume the "other" company will take care of removing the users/devices from their BES server (that way they can free up some licenses).
Before you proceed to activate the devices on the new BES, ensure they (the other company) haven't de-registered the devices with the local provider.

Devices haven't been de-reg as they are all working fine at present on the old bes. The "other" company is our parent company but they have "resource" issues and cant remove users as and when they are migrated as this will take place over a 2 week period.

The plan was I wipe handhelds add them to the new Bes server and then once all are up and running on our bes they remove all at their own leisure from there Bes server.

I did a security wipe of 1 to test tried the enterprise activation but it never got starter.

Do I need to have any specific ports open on the firewall (inbound and Outbound ) for wireless activation.

Have you tested the connection to the RIM srp host with the new BES? There's a tool (bbsrptest.exe) in the following directory : C:\Program Files\Research In Motion\BlackBerry Enterprise Server\Utility that's used.
If you've received a successful response, then your BES is connecting thru the firewall on port 3101 to the srp host (srp.xx.blackberry.net) at RIM.
Take a look at the Blackberry manager to see wht's the status of the BES server. Also have a look at the event viewer for any errors associated with the BES services.
There may be several other reasons why EA is not progressing or starting.
Are there any mail re-direction rules/filters in the inbox of the test user account?
Is there any anti-spam software running locally on the desktop of the user account? This may trap the @etp message sent from the wireless network to the device. Receipt of this message on the device (after being re-directed from Inbox-->device) is necessary for EA to take place.

Did you set an activation password for the user account?

Make sure they remove all the users from the old BES. After the HH is wiped it won't try to communicate with the BES but the BES will still send it email and the handheld will pop up a decryption failure each time.