Taxi Call Centre

I want to build an intelligent system for a local taxi office. They have 4 lines.

I want to expand this to 10 lines.

Can I put 10 linejack cards into two pcs and allow other people on the local lan to answer these calls via a pc?

Does the existing free software cope for this?

I want to build a system where telephoist can snswer any call and then automatically pull up the customer details via callerid.

Will each pc require a full duplex sound card as well?