Jack in, known as plug in (プラグイン?) in Japan, is the action of an operator transmitting his or her NetNavi from the PET into the cyberworld. In the first three Mega Man Battle Network games, the PET used a wire that plugged into the port of an electrical unit. From Mega Man Battle Network 4 onward, all Navis jacked in wirelessly. To jack in with MegaMan.EXE in the games, Lan Hikari would have to be standing considerable close to the jack in port. Jack out, plug out (プラグアウト?) in Japan, is the opposite operation.
When a Navi is in the cyber world, the operator can disconnect without jacking them out but they cannot send Battle Chips to their Navi without a connection. Also, if a Navi loses its connection with its operator, the Navi can only jack out by manually returning to the original jack in site.
In Mega Man Battle Network 2, Lan receives a wireless port adapter from Mayl before leaving to Netopia. Lan uses this twice. Once when a port is out of reach due to a trap and the other that was too far to reach without going near Princess Pride. The wireless adapter allows MegaMan to jack in through the "wireless field". The wireless is essentially the predecessor to the wireless PET's introduced in Mega Man Battle Network 4 on.
In the Japanese version of both the games and MegaMan NT Warrior anime series, Lan (Netto) is the only character who includes ".EXE" whenever he plugs in. In the English version Lan only does this in the first game.
Most operators call a sort of battle cry before they jack in their NetNavi by yelling out their Navi's name.
- "Jack in!! MegaMan.EXE, transmit!" - Lan Hikari, Mega Man Battle Network.
- "Jack in!! MegaMan, Execute!" - Lan Hikari, Mega Man Battle Network 2-6. Exclamation marks vary in some games. MegaMan is temporarily replaced by ProtoMan or Colonel in Mega Man Battle Network 5.
- Jack in!! MegaMan! Power up! - Lan Hikari, anime and manga.
- "Plug in!! Rockman.EXE, transmission!" (「プラグイン！！ ロックマン.EXE、トランスミッション！」?) - Lan Hikari (Netto Hikari), Japanese quote.