Multiple USB modem connect to increase Banwidth

I have two 3G usb modem . I want to increase bandwidth using two modem at a time.I dont want to use additional usb hub.

I have seen some tutotial about BONDING and TEAMING. but those are for multiple ethernet (eth0 ,eth1) bonding. Is it possible to do this work using USB modem which give me ppp0/ppp1 networking port.

when i connect modem using there driver software ppp0 and ppp1 show in ifconfig command.