>Hi. I have two people trying to sell me a contract for HiSpeed Internet for my 20-user network.
>#1 wants $895/mo for (2) T1 lines and 16 phone lines (voip)
>#2 wants 450/mo for (1) DSL line and the same phone lines.
>
>I am a bit skeptical about the DSL matching performance of the (2) T1's
>
>Any opinions?
>
>Thanks, Randy
>
>ps: I have (1) T1 now with voip

My understanding of the differences:

T1 is symmetric - upload speed is the same as download speed. DSL is usually asymmetric (i.e. ADSL) unless you spend fairly big $ for symmetric (SDSL). With ADSL upload speed is only a fraction of download speed (sometimes as low as 25%). If you have significant upload requirements (e.g. if you're hosting a busy Web site) T1 may be more appropriate. On the other hand, if most of your traffic is download, DSL may give you higher speed for less money.

T1s often have more stringent Service Level Agreements (SLAs) e.g. they may guarantee 4 9s uptime, whereas you might get only 3 9s guarantee with DSL (or maybe no uptime guarantee at all). In general T1s are touted to offer higher Quality of Service (QoS).

DSL speed can vary - it can slow down when the Internet in general is busy whereas T1 speed is generally constant (again, higher/more consistent QoS).

T1s are usually priced such that you can saturate them with traffic 24/7 and the telco won't bat an eye. OTOH with DSL you may have to watch out for extra traffic charges if your usage is "heavy" i.e. above some arbitrarily-set level that may change without notice unless your contract says otherwise.