For T1 circuits, carriers will typically allocate up to and above a full class C (254 usable addresses) depending on justification. IP Addresses are given in increments of 4, 8, 16, 32, 64, 128, 256, etc.
For DSL, carriers will typically allocate 1 IP address and up to as many as 10 addresses, in some cases for an additional fee. NAT can often be used to make more addresses available internally.
