Our office is migrating to IP telephony. We have less than 10 employees that will be using the phones. We currently have cable internet, and they just bumped the speeds:

There is a data center that was just recently built in our building, and we were considering co-lo'ing there in the near future. As a result, they offered us access to their triple-redundant internet, but it's quite expensive. They are offering 3mbps committed with up to 10mbps burst for $250/month (discounted). We pay ~$120 for our cable (which the plan was to keep--at least for TV).

I want the phone system and LAN to be as separate as possible. Was thinking about keeping the cable for LAN, and using the other connection for the phones (until I saw the price). Now I'm thinking it might make sense to add on to our existing cable setup, and change our phone to only have DSL as a backup for the cable.

Is there any real benefit to the fiber? Especially for the price? Any other suggestions or ideas?

Thanks.