need some advice- Mobile says Inactive Sim

[Willin08]

if it says inactive sim, theres several reasons as i occured to it too:
-check if the sim works on other phones as some sims such as 02 expire or needs activating
-to check if its unlocked *>*<<*< (works for most sony ericsson phones), service info then simlock then check if all locks are unlocked if their locked phone may need to be unlocked.
using the sim-lock patch which might work.
-the i-mei might be blocked which all networks are blocked even if you unlocked it and have a working sim, only way is by changing the imei no. which is illegal (which iam asking help for a k750i?)

1. K850 is DB3150, there is no patch unlocking and no free way to unlock it. Only with setool box or servers.
2. There is no repair/changing IMEI on K850 (DB3150), at least not for public.

The best thing is to check the service info and SIMlocks. They must be all opened to have an unlocked phone.