Since the Nexus One isn't directly available in UK yet, it doesn't come with the settings needed for automatically getting it online (via GPRS, EDGE, 3G or HSDPA) and sending MMS in the British networks. The settings depend on your provider and your tariff (prepaid or contract). I'm on the "Online simplicity 10" tariff of O2 with unlimited web bolt on, which I assume falls in the category of contract tariffs. After trying out various settings found on the internet, I finally found one where both browsing and MMS works for me.

In order to set up the information for a new APN (Access Point Name), proceed as follows: First, navigate to the Settings screen of Android, e.g. by pressing the Options button while being at the main screen. Then

"Wireless & networks" → "Mobile networks" → "Access Point Names" → press Options button → "New APN"

and enter the following information:

Name: O2 UK Postpay
Proxy: <Not set>
Port: <Not set>
Username: O2wap
Password: password
MMS Proxy:
MMS Port: 8080
MCC: 234
MNC: 10
Authentication type: None
APN type: <Not set>

After saving these settings you need to make sure that the settings are used by selecting them in the list of APNs. The grey dot next to "O2 UK Postpay" should then have a green dot in its middle. It will take a few moments until the phone registers these settings and connects to the network. Some people have reported that sending MMS can fail, because O2's network is not properly configured for allowing the large camera pictures of some phones, but I didn't experience any such problems. Either O2 has finally updated their phone database, or it's because the N1 automatically resizes large pictures before sending them as MMS.

It should be noted that in its current state the 3G reception of the Nexus One leaves much to be desired. The reception can be unstable even in areas with strong signal, with frequent switching between GPRS/EDGE and 3G. A software update to relieve this issue is expected soon, and until then these workarounds are reported to work for many people:

1. "Wireless & networks" → "Mobile networks" → "Network Operators" → "Select automatically"

2. Prevent the phone from falling back to GPRS/EDGE by forcing it to use 3G. For this, access the internal settings by dialling *#*#4636#*#*. Now go to "Phone information" and change "WCDMA preferred" to "WCDMA only".