Nokia's amazing E51 has has finally made it into my pocket!
Upgrading from the E50, there was only one reason for my purchase. Built in VOIP capabilities. As well as all the usual features for a Nokia E (business series) phone, including integration with Microsoft Exchange, bluetooth etc, one of it's biggest marketing points on the Nokia website is it's VOIP integration.
Given how much attention they give to this feature, you'd expect it to work really well out of the box!
It took 2 days of playing to find the options in the software (after all, who reads the manual anyway, and the girls in the shop hadn't a clue where to find it!), and I eagerly inputted my details for my sipgate account, expecting instant cheap phone calls.
Except that nothing worked.
No cheap phone calls for me!

So I tried installing Gizmo, a 3rd party program. However, being unwilling to pay for a gizmo account, since I really only wanted to use my sipgate local number linked to my business, I moved swiftly on to Fring. I entered my details, the phone registered with sipgate, and away I went. First call to the house to test quality. Hello? Hello? HELLO?
They could hear me, I couldn't hear them. Not good!
Restart the phone, and we can both hear each other. Sometimes. Very poor call quality.

So I set out on a mission. The right settings had to be out there somewhere! And they were, at least, for some other VOIP provider. Some modifications, and SUCCESS! Perfect call clarity and handling!
Best of all, I haven't had to touch my router config.

So for anyone searching for sipgate settings for the E51, here they are:
Profile Name: Sipgate
Service Profile: IETF
Default Access Point: Whatever your access point name is.
Public user name: sip: XXXXXXX@sipgate.co.uk <-ignore the space. It turns into a smiley without it!
Use Compression: No
Registration: Always on
Use Security: no

Proxy Server:
Proxy Server Address: sip:sipgate.co.uk
Realm: sipgate.co.uk
Username: XXXXXXX
Password: XXXX
Allow loose routing: yes
Transport Type: UDP
Port: 5060

Registrar Server:
Registrar server address: sip:sipgate.co.uk
Realm: sipgate.co.uk
User name: XXXXXXX
Password: XXXX
Transport Type: UDP
Port: 5060

Thanks to Egypt of the nokia forum for providing the basis for working these settings out!