You could connect to Xbox live if you had one of the undetectable modchips with a switch that allowed you to flop between regular and modded firmware. Even with modded firmware you could go on live for a while, even cheat at multiplayer games flying around and stuff until you got banned.
ironically, the modchips were only "undetectable" because MS never thought a KV (the keyvault containing the RSA keypair tied to that mobo serial) would not match the motherboard it ran on.
The first players to use a xenon keyvault on a jasper mobo got away with it for years just because MS overlooked a decent assumption.
