Try these...
Connection Name: t-zones
Data Bearer: GPRS
Access point name: wap.voicestream.com
User name: Nokia
Prompt Password: No
Password: none
Authentication: Normal
Homepage: http://wap.myvoicestream.com
Gateway IP Address: 216.155.165.50
Connection Security: Off
Session Mode...
If you change the net settings the phone will be unlocked. All of the N-Gages are unlocked to begin with, however you just need to change the net settings for it to work with whatever carrier you have. I have a T-Mobile N-Gage and just by changing the net settings I now use my Cingular sim...
Got it directly from the N-Gage site...
T-Mobile Internet Settings
How to set your Internet access settings.
1. Press the Menu key.
2. Highlight Web
3. Press Options
4. Select Open
5. Press Options
6. Select Settings
7. Highlight Default access point
8. Press Options
9. Select Change
10...
It just allows you to use whatever sim you would like. For the N-Gage it only allows GSM, so either Cingular or T-Mobile, and some other oversea carriers. So if you have a T-Mobile phone, you can unlock so it is Cingular phone. I don't know that helps.
Think of it this way:
You have one of...
If you remove the battery from the back of the phone it should tell you what version you have. You might be able to find out if you press, I believe it is *#0000#. This will give you the version number of the phone which should have that listed. I think that the RH29, was the european version...
I am pretty sure that if you did not have one in the phone, you would not be able to use the phone. There would be a message saying insert the sim card.
You should be able to use your old Nokia charger, though it might take a little longer to charge depending on what type of charger it is. If it is a 7U it will take a bit longer than a 12U. The 12U is the type that comes packaged with the N-Gage.
Edit: Ashram beat me to it :)