Question : what ports need to be connected for Cisco 2811 on network

Hi
I've asked this question twice already without being able to resolve it

Hi
I have been trying to connect a 7940 at a remote user behind a Draytek 2820 adsl router to a cisco 2811 switch. which is also behind a Draytek 2820
First of all I amended the configurion of the 2811 on local site and connected the new 7940 handset - works
Then I connected it to a second adsl router on site (effectively a remote site with its own IP)
(That is not the ultimate intention but at least I can test without having to travel!)
The 7940 loops between 'configuring CMList and looking for TFTP server. I reset it to defaults in accordance with instructions I found when googling but got stuck at 'configure SIP settings' The TFTP setting on the 7940 is the external IP of the local site with the 2811. I suspect it does not get past the Draytek, but I don't know what port it requires.

What does a remote 7940 need in order to connect to a local 2811
What ports need to be opened in the firewall (Draytek 2820 on both remote and local network)
What changes are needed on the cisco 2811 to allow this.

Answer : what ports need to be connected for Cisco 2811 on network

are the phones using DHCP for tftp address or are they manually set in the phone?  you may need to change your OPTION 150 setting in DHCP on the remote side if using DHCP-issued TFTP/Callmanager address type of setup.