My old Pay as you go button phone will not accept the new SIM card. Siemens is not on the list of manufacturers supported.
Message on the phone is: disabled! NETWORK LOCK
I raised this issue with Virgin one. week ago, but have had no reply.
Where did you purchase the handset from originally ?
I am sorry we wouldn't be able to help getting this unlocked to allow the Sim to work, sometimes for older phones you may be able to find an unlock code online.