When my cellphone accesses a website via the tower and its GPRS gateway, NAT ensures that the sites receive a public IP. Would all phones using a single tower have the same IP?
- If yes, then how can the mass of received HTTP data routed to the correct cellphone? And how can websites differentiate between cellphone visitors? Is there additional HTTP header data?
- If no, then how are these unique IPs assigned? Based on availability or location? Would each tower have a fixed set of IPs?
To answer your first question mobile/cell-phone IP addresses are handed out using DHCP like any other client device. To answer your second questions, well yes, through NAT - that's what NAT does, it allows multiple 'inside' devices to get IP services through a NAT gateway - external IP services will not be able to identify individual internal devices like phones by IP but could via a session ID, cookie or similar.