[c-nsp] Inbound redundancy with two ISPs

[The Father]

One of our customers is looking to us to provide a failover method for 
their two internet access links.  Normally this wouldn't be a problem 
but the customer has public IPs that were assigned to them from ISP-A 
(we're ISP-B) and they use them for servers behind ISP-B's connection.  
They would like it so that when ISP-A goes down, the link that we 
provide becomes primary and inbound and outbound traffic.  Does anyone 
know of a Cisco (or other vendor) solution that could take care of 
this?  I've tried explaining that for customers in these situations, BGP 
and public ASN/CIDR blocks are what's normally required for this to work.

Thanks.

Jose