Bonding for speed
More Download Speed
AAISP use FireBrick FB6000 routers to manage ADSL connections. This manages the bonding of traffic from AAISP to your location. IP blocks (configured on Clueless) can be routed to multiple lines on your login. for fallback, the FB6000 will stop routing IPs down a line that is off line, and from the Control Pages you can control which lines are used. Speed wise, the FB6000 will route based on the speed of the line - so if you have a 10M line and a 5M line, then the traffic will be weighted correctly (i.e. 1/3 on the 5M line, and 2/3 on the 10M line.)
More upload speed
Upload bonding requires a device at your side to route IP packet up alternate lines. Typically a FireBrick can do this, as well as provide fallback (not using a line that is down) and firewalling. AAISP staff can also configure the Firebrick for your lines for a nominal fee.
There are other devices that can do this, some of the Mikrotik range of routers can do this.
Linux is capable of doing both basic upload bonding by multipath routing. It can also do sophisticated upload bonding using a combination of policy routing and firewall rules.
See Category:Bonding Configuration for example configurations for various routers.