Segestion on new setup

[system]

Hi
I want to start a new company that provide international calls only
I want the user to be able to call a spesific phone number and without entering any pins the system will recognize the user by his caller ID. (Is This possible)
The second thing i want the user to be able to use a call back service. i.e: the user enter to manage his account online and from there he inputes his phone number and the number he wants to call and the system will connect the user (Is This possible)
Now should i use Asterisk or AsteriskNow.

also what type of hardware do i need other than the servers and switches, do i need any of digium cards?
could you please be specific with your answer because im new to this system.
Thanks for help

[navaismo]

want the user to be able to call a specific phone number and without entering any pins the system will recognize the user by his caller ID. (Is This possible)

Yes its possible, you need to read the CALLERID(num) to set your routes.

the user enter to manage his account online and from there he inputs his phone number and the number he wants to call and the system will connect the user (Is This possible)

Its possible too, i.e. Integrate your webpage with asterisk using AMI and take a look in click2call.

also what type of hardware do i need other than the servers and switches, do i need any of digium cards?

You can use a Landline an buy some digium card or you can buy a SIP Trunk this only need a good INTERNET connection.