Bandwidth Aggregation with multiple 3G cards?

I have multiple 3G data Cards as well as a wired connection to the Internet. I can connect each of them separately and access the internet. Is there any way i can aggregate the bandwidth of these cards to enjoy the combined speed? What i mean is simultaneously plugging in all the cards and getting the sum total of the bandwidth.

You could do this. Network Manager can do one connection per device just fine. But even with network-manager connected to multiple things, outbound traffic will only chose one gateway. You need to bridge these gateways into a virtual tunnel and use that as the gateway.

The problem is all the machinery is there (iptables, ipchains, iproute2, etc) is somewhat lower-level than network manager. You can try and follow a guide showing example configuration to split traffic over multiple gateways but network-manager might end up getting in the way.

It might not. It might work out just fine. You won't know until you've poked it ;)

No, you can't aggregate multiple data cards out-of-the-box.

You need to buy a device that does link aggregation(802.3ad protocol).