Cannot enable LTE on Xperia SP C5303

[BW1]

Hi - I have an unbranded Xperia SP C5303 and I've recently taken out a SIM-only plan with Three UK.  Although I have a 4G enabled SIM, I cannot see the 4G/LTE option in the phone settings.  If I put my SIM card into an Xperia Z1, I can see the option and successfully connect to the 4G signal.  My phone is still on Android 4.1.2.  I used the Sony online chat support, but they didn't know why I can't see the 4G option, and suggested I do a 'repair' using PCC, but I'd really prefer not to do that, because I don't trust that it will properly restore all of my data.  Has anyone else had this issue?

[_alexdon_]

Try settings-mobile networks-network mode-4G.

[BW1]

Hi, thanks for the quick response.  Unfortunately I don't have "Personalization" as a menu item in Settings.  The only way I can see the Nework Mode setting is in Settings->More->Mobile Networks->Network Mode.   However I'm not given 4G/LTE as an option, I can only select WCDMA or GSM or both.

[_alexdon_]

Strange.Force shutdown your device and look for it again.

http://userguide.sonymobile.com/referrer.php?region=global-en&product=xperia-sp#!Turning-on-or-off-t...

[Uliwooly]

Are you certain that you have the C5303 because if you have the C5302 its not LTE capable, is your phone locked to a carrier/network branded? 

[BW1]

Thanks - still no luck unfortunately.  What I've found is that starting up my phone without any SIM card, I can see the 4G LTE option, and even find a list of 4G signals when I do a carrier search.  However, with my SIM card in the phone, the 4G option is gone, and I can only select WCDMA or GSM.  I assumed it had something to do with my SIM, but I've tried it in other phones such as the Z1 and the Nexus 5, and they work fine on 4G with my SIM.  Very strange!

[_alexdon_]

It could be related to your SIM.Contact your network carrier.

[Uliwooly]

is your phone network branded/carrier locked?

[BW1]

I don't believe so.  I bought it from Phones4u, and originally I used it on O2, then I switched to Three UK.  I wonder if somehow O2 did something to disable 4G?  The customization number is 1272-4687_R13A  which I believe translates to 'UK Generic'.

[_alexdon_]

Dial *#*#7378423#*#*-service info-sim lock.Tell the results.