IMEI collection problem and virtual power

Hi to all, I have problem with collecting imei numbers of cellphones which try to register to the nanoBTS. All imsi numbers of subscribers are saved in Subscriber table but only very small number of imei numbers are stored. What do you thin about this? Could you offer any solution. Moreover, I want to ask something about virtual power. Is there virtual power property (for example my actual power is tx 100mW but MS feels that it is 10W). If we have how can I use it? Thanks. Jason