This should work. Since we are using two HWIC cards (two wan interfaces), its is equivalent to two point to point links to the same destination. So this can either be used for backup/ redundancy or increasing the total throughput.
Thks for your reply. Yes my thoughts also. Given the limited bandwidth of 3G you'd think there would be mention of this technique by Cisco. Might have to give it a try.
Keep in mind that if both 3G cards connect to the same carrier, you are not doubling the bandwidth. If you want to double bandwidth, you will need to use two different carriers.
Thanks Roman, but if I use a different framed-route (attrib 22) with each connection the carrier has no idea that the two connections come from the same physical device. Then I just use IOS smarts to route the traffic.