loadbalancing in OSPF with VOIP

Hi Guys

I have a company that has branches in 6 regions.Two service providers provide the WAN connection accross with one of (10megs) being the main link and the other 64 kbps provides the backup.

They run OSPF as an IGP across.

We have configured OSPF automatic failover with Kenstream (backup). We need each branch router to be configured such that in the event of KDN (main link) failure and Kenstream picks up, VOIP data shall not be let through as voip takes more bandwidth making the 64 K kenstream link Unusable.

On resuming of KDN, VOIP should be allowed to go thro.

Any ideas on how 2 go about this?

masomoz