I recently tried to force my nexus-s to use a 3G network in an area where it kept swapping between 2g/3g coverage… This can be done via a ‘hidden’ phone menu which you can access by dialling:
Go to ‘Phone Information’ and then you can select your preferred network or lock it to WSCMDA Only in my case. The down side of doing this as I discovered 48 hours later is that I now couldn’t send any SMS messages at all. The phone would fail with ‘message cannot be sent’ and reboots, restarts or plugging in settings in the APN sections of the phone accomplished nothing.
A quick call to Optus revealed that this wasn’t a change on their side so it was clearly something to do with the settings I had messed with.
After a lot of trial and error it turns out that the problem was my Optus Message Centre had somehow been reset, the solution is to enter it again in the same menu.
1. Dial *#*#4636#*#*
2. Goto Phone Information and then find the section SMSC and you need to enter the Optus SMSC number which is +61411990001. However this still won’t work as you need to convert this to hexadecimal PDU which is apparently what the nexus-s speaks… to do this:
3. Use the form on this page: http://www.twit88.com/home/utility/sms-pdu-encode-decode
4. So for Optus you would generate the following HEX PDU: 07911614910900F1110000910000AA00, the code you actuall enter is 07911614910900F1 (the rest is just timestamp stuff and can be ignored).
5. Hit ‘update’
Finally you can send messages again!