Getting 2G/3G working is not well documented and requires enabling the -devel repos.

With the current code and known bugs, you will have to (from memory):

1. enable the -devel repos, apt-get update && apt-get upgrade
2. install hildon-connectivity-mobile
3. restart the phone, wait for 1-2 minutes depending on the phone
4. 'sudo service ofono restart'
5. If your sim has a pin, run "startup-pin-query" as user, fill in the pin
6. run 'sudo service icd2 restart' just to be sure
7. Then touch the status bar, go to internet connections. >>this will currently online your modem<<
8. Wait for the modem to go online, and then if you search for connections again, your data connection should be provisioned.
9. Select the data connection, and it will fail instantly -- but it doesn't actually fail. (this is a known bug and I will fix it next week)
10. Wait 10 seconds and try again, then it should work

Steps 4 - 10 you will have to repeat every time you boot the phone. after that, only 9-10 should be required.

If all of this seems like too much work -- you're right, it is. There's a combination of problems:

1. ofono on the d4 is a bit buggy still - which causes several problems
2. libicd-network-ofono doesn't wait for the connection context to become active, it assumes the call is blocking, which it is not (I know how to fix this)
3. nothing currently is responsible for making the modem online, icd2 does it currently when the user searches for networks, which is not the right place, but it's a start

Nevertheless, I do this all the time, and it's slowly getting easier, more reliable, and less work.