Sharing/Join 2 Broadband Internet Connection to 1 connection

[d4n13l]

I have one broadband connections to ISP A with bandwith 128Kbps. Now, I want to add a new connection to another ISP(B) with 128Kbps too. So, actually
I will have 2 connection to internet with different ISP with 128 Kbps each.

My Question is
1. how to join the 2 connection that, so I will have 256Kbps connection?

2. If the connection to ISP A or B be down, I still have 128Kbps connection.
So It's like a backup connection too, how to do that?

Thank's in advance.

[LooseChippings]

This doesn't sound feasible because you have 2 different lines each at a maximum of 128 kbs.

[braindead]

If you already have two seperate connections then why would you want to join them? Sounds like you're trying to do one of those very old and outdated dual modem hookups to double your speed.