Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Don't waste your time

The Comswitch 5500 works great if you have a single line phone, with no extensions, no caller ID and no DSL on the line. Then it is quite capable of discerning fax calls from voice calls. But if that's the extent of your setup, you may not really need to buy an additional piece of equipment.However, if you have any of those other things, be prepared for the following:* DSL on the line will require 3 to 5 filters to prevent static. The usual is 1 filter, the manual tells you 2 filters but customer support and actual experience will tell you 3 to 5 filters are required (at $10 to $20 each if you don't happen to have a bunch of them not in use).* If you have more than one phone extension, be prepared for the phones that aren't connected to the 5500 to ring once and stop.* If you have caller ID, be prepared for it to display during the first ring only - on all phone extensions.I was not prepared to deal with all of those conditions and returned the machine for a refund.