Vodafone GPRS Internet settings:

Homepage: http://wap:1999/vodafone.wml
Access Point (APN) address : Internet
Username : web
Prompt Password: no
Password: web
Session type: Continuous / permanent
Authentication: Normal
Security: Off

Note: GPRS subscription must be enabled for "Vodafone Internet Access Service".
Contact Vodafone Customer Services to get this enabled.

O2 GPRS Mobile Web settings:

Homepage: http://pda.o2.co.uk/
APN address: mobile.o2.co.uk
Username: mobileweb
Password: password
Session type: Continuous / permanent
Authentication: Normal
Security: Off

Note: The "Mobile Web" service must be enabled for these settings to work.
Contact O2 Customer Services to get this enabled.

Orange GPRS Internet Settings:

Homepage: http://orange.multimedia/
APN address: orangeinternet
Username: [leave blank]
Password: [leave blank]
Authentication: Normal