Can a fax machine slow down my internet connection?
No. If you understand how DSL works, you’ll understand why it won’t interfere. Basically, fax sends data down the phone line on the same frequency as voice. Knowing that, you could also ask the question “Does talking on the phone disrupt Internet speeds?” and the answer to that is also no. How DSL works is copper wire will carry data transmitted on different frequencies. That’s what the splitter is all about. It splits the lower voice transmission frequencies from the higher data frequencies. In that way, they both work on the line completely independent and separated form each other. If you’ve got a poor splitter, you may hear a bit of static when talking on the phone and it may interfere with fax transmissions but it won’t slow you down.
