You won't need the air interface - hypothetically just an appropriately rooted femtocell, carrier HSS/HLR/MME that can authn/authz you, and Asterisk server that

You won't need the air interface - hypothetically just an appropriately rooted femtocell, carrier HSS/HLR/MME that can authn/authz you, and Asterisk server that is secure. Or a flooded Nokia Flexi on a rack shelf, I mean, they look cool, don't they...