[Q] Help!! Keep loosing Signal and baseband switches to unknown

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http://forum.xda-developers.com – Hi Hopefully someone will be able to help me this. I have just got a Optimus 4x HD and i seem to have a persistent problem of suddenly phone say no sim inserted even when a sim is inserted. Then I restart and sometimes problem is fixed, at other times nothing happens, i check the information under settings and under baseband it says unknown. :( The IMEI is also not shown :( someone please help me!! I have changed software from ICS to JB then thought it was an issue with JB but problem is with all software :/ (HowTos)