QoS for VoIP on a "burstable" shared leased line
So, a customer of mine just moved into a managed office, and the internet line is apparently a 30mbit/s line. We've been told we're guaranteed a 1mbit/s throughput however.
I need to balance the use of VoIP and web browsing by the customers on this line (which during today's testing was only giving circa 1mbit/s during the day, and is currently giving me 17mbit/s after hours as I pull down big ISO files).
What would be the best idea to ensure the VoIP calls aren't screwed whilst hopefully taking advantage of the (hardly) burstable nature of the pipe? i.e. I know I could set the limits at 1mbit/s or slightly under and ensure VoIP worked, but it wouldn't make for a happy customer when he can't watch films etc when he's bored.
Should I even bother with traffic shaping given the apparent 1mbit/s guarantee? or is that just asking for trouble?