I know nothing about unlocking
1)I have seen some shops offer this service,is it illgit?
2)Will I lose all my pictures on my phone?
3)If it's unlocked does this mean I can just buy a monthly or pay as you go sim?
thanks

1. Unlocking is completely legal (you are just removing the SIM locks so a phone can be used on any network)
Unblocking is illegal (changing IMEI numbers so that phones that have been reported lost/missing/stolen will work again)

2. It depends on the phone, some just need a code entering, others need the entire software on the phone changing.

3. If it's unlocked (and not blocked by the networks) then you can use any other SIM, although THREE SIM cards don't always work as some need a different voltage, and only work in 3G phones not 2G ones.

Hope this helps.

I had a sony experia unlocked and it didn't work with my new sim (my old one still worked though)

Unless your new sim was a THREE sim then it's possible your phone wasn't unlocked, or wasn't done properly.

Well it was on orange, unblocked it and the new virgin SIM did not work, tried my mates T-Mobile SIM and that worked in it

If a phone is on Orange then a T-Mobile sim will work in it without it being unlocked, as they are now one company, EE.

If the phone was locked to Orange then the Virgin sim wouldn't work in it, however if it was locked to T-Mobile it would, as Virgin piggyback on the T-Mobile network.

Hope that makes sense.

correct Dr
now it makes sense
how did I miss that?