I have been asked to analyze the bandwidth usage of a company and make a recommendation for upgrading their Internet connection(s).

Here is the layout

3 DLS lines so it is 3x(6 Down, 1 Up Each) into a load balancer out to the office's network.

30 VOIP phones run on a T1 (1.5 Down, 1.5 Up)

The users at the company are heavily uploading. It is my suspicion that the issue in slowdown is being cause by multiple people uploading and others not being able to get requests out for even simple http requests.

My initial idea is to get them a fiber line with a 10 down and 10 up. What do others think on this plan? Will that be enough to host their network traffic? What do I do about the VOIP line afterward? The fiber is expensive and I know the T1 does a great job for their VOIP so I do not want to suggest a DSL line because I know it may not be sufficient. I would also like to save them some money if I can. Maybe even get a faster fiber line and forgo the T1. Though I know their load balance/switch can only handle 20MB/S throughput.

Looking for some confirmation/suggestions on my plan.

I am planning on going in to get some real diagnostic numbers. Any suggestions on software to use for that? Preferably Windows software.