A method of providing connectivity to a vehicle, the method comprising at a first device configured to be aboard the vehicle: establishing at least one first connection with at least one first network, said at least one first connection allowing communication with a second device (7a, 7b) configured to be remote from said first device; transmitting via said at least one first connection an allocation request to said second device (7a, 7b); receiving via said at least one first connection an allocation response from said second device (7a, 7b), said allocation response indicating a first authentication device from a plurality of authentication devices remote from said first device; switching between a first state in which a first modem of said first device uses an authentication device co-located with the first device to a second state in which said first modem uses said first authentication device and a second modem of said first device uses a second authentication device co-located with the first device; establishing with said first modem a second connection with a network and authenticating said first device on the network using said first authentication device, authenticating said first device on the network comprising transmitting authentication data between said first device and said first authentication device via said at least one first connection; receiving an indication of a third authentication device from said plurality of authentication devices remote from said first device; switching to a third state in which said second modem uses said third authentication device; and establishing with said second modem a third connection with a third network and authenticating said first device on said third network using said third authentication device. establishing at least one first connection with at least one first network, said at least one first connection allowing communication with a second device (7a, 7b) configured to be remote from said first device; transmitting via said at least one first connection an allocation request to said second device (7a, 7b); receiving via said at least one first connection an allocation response from said second device (7a, 7b), said allocation response indicating a first authentication device from a plurality of authentication devices remote from said first device; switching between a first state in which a first modem of said first device uses an authentication device co-located with the first device to a second state in which said first modem uses said first authentication device and a second modem of said first device uses a second authentication device co-located with the first device; establishing with said first modem a second connection with a network and authenticating said first device on the network using said first authentication device, authenticating said first device on the network comprising transmitting authentication data between said first device and said first authentication device via said at least one first connection; receiving an indication of a third authentication device from said plurality of authentication devices remote from said first device; switching to a third state in which said second modem uses said third authentication device; and establishing with said second modem a third connection with a third network and authenticating said first device on said third network using said third authentication device.