I can access exchange from internal ip address address but not external

Question

Hi there, been trying to set up my iphone to collect my email from my exchange server 2003 sp 2 and have been having huge problems.
My IT guys we use have done everything they can so far and we tried setting up the email by connecting through my wireless network and on my intenal ip address to by pass my westell router and it works.
Now as soon as we try this outside and turn off the wi-fi and change ip adress to external, basically my OWA web address the verification fails.
We use an actual number like 000.00.00.000 rather than this webmail.mycompany.com etc I have read about. Sorry not very good at this sort of thing so sorry if I sound like a novice.
Any help appreciated.

Answer 1

In order to connect to an Exchange server from internal and external, you must connect via a URL and not a specific IP address.
The reason for this is that internal IP addresses (10.10.x.x, 192.168.x.x) are different than external IP addresses, therefore you will not be able to connect externally as you reported.
If you connect to Exchange using a URL (example: http://mail.domain.com, the URL is mapped to both the internal IP and external IP - and thus the iPhone will work everywhere. Internal mapping is done in the server's DNS records. External mapping is done by contacting your internet provider and adding an A record. (You will also need a firewall mapping from external to internal with port 80 open for incoming traffic.)
When you set it up as above, it works like a champ on Edge/3G and WiFi whether your in the office or outside.