sos

Hiya I recently bought a blackberry bold 9900 from a woman on the site gumtree. She told me it was 2 years old and locked to the vodafone network. Came home put my brothers vodafone sim card in it and its not accepting it. It comes up insert sim card with the sos in the corner where the signal indicator should be. I noticed that in the sevice status that it jumps providers. Going from vodafone to o2 to tmobile and 3uk. Can anyone help me find out what the problem is?