I just wanted to know if I can port my cell phone number to asterisk system or not.
I guess that it would be down to your VOIP ITSP
Asterisk is not a telco, numbers can only be ported between telcos.
You can add GSM PCI (example) card then Asterisk will handle Your cell phone numer.
<.< That is to use old cellphones as handsets for asterisk. If you do that you will have an extremely small calling area and not only that but you still need to have your number coming in through a phone line.