2 broadband providers on 1 network?

[h2009]

You could use a load balancing router - i.e. set certain traffic i.e. SIP to one connection and all other traffic to another.
The other option is to allow 2 networks to run (VLAN) and send the VOIP lan over to another connection, best done via hardware
have a look at monowall (i've heard that this can be used to both options above)

 

[h2009]

Oh in addition,
does your client need two connection?
The reason why i ask this is because since i've put in QoS and CoS, i've never looked back at it. My situation was getting to point where i was so sure i need more than 1 broadband connection i start to install another, but after putting in QoS and CoS on the brand new layer 3 Netgear switchs its completely removed any kind of need for this.