I found in one form that.. Cisco 881G router will support ADSL as primary and 3G as backup using IP sla.
The below information from that forum
"I will then have a TCL script that will activate when the 3g activates to email me of the failover event. This will give me time to up the usage plan. My plans are to get a $0 3g connection, yes the per mb cost will be prohibitively expensive, but from what I hear if you switch plans within 48 hours of using data, the data you used will count towards the plan. So when it does failover, I'll probably change it to a 3gb plan. Then drop it back to $0 when the adsl connection is stable again.
This is so then I have an active sim that I can use in emergency without having to keep paying for a 3g connection with data that I wouldn't be using"
Experts, can some one tell me how I have to confirue my 881g router accordingly to function failover between adsl & 3g.
Thanks in advance.