sure, you can sell it directly or use the number to change the virtual money in many game stations in the net. hehe, I had done many times a long time ago. At that time, I can register OICQ number for free in Canada, but most people can't in China. THey have to pay to get a new one. However, from the middle of last year, whether you are in China or abroad have to pay for registering a new number.
The user of digits5 should be very early one of OICQ.
because you didn't upgrade your OICQ software.
If you still use the old version, you can get new one for free.
But if you upgrate software, you can't
the latest verion of OICQ provide many new functions. You can have a try, they are really funny!