A phone number and a fax number look identical — but they work very differently. This guide explains the relationship between the two, when to share a line vs. keep them separate, and how to get a dedicated fax number without buying any hardware.
Frequently Asked Questions
Is a fax number the same as a phone number?
A fax number and a phone number follow the same 10-digit numbering plan and are assigned by the same authority. The difference is functional — a fax number has a fax machine or online fax service connected to it, while a phone number connects to a voice handset. You cannot tell them apart just by looking at the digits.
Can a phone number and fax number be the same?
Yes, one physical line can serve both purposes, but it requires special configuration. The most common methods are Distinctive Ring (DRPD) — where the phone company assigns a second number to the same line with a different ring pattern — or using a [virtual fax service](/blog/virtual-fax-number/) that handles faxes without tying up the voice line.
Do I need a landline to get a fax number?
No. Online fax services like [mFax](https://mfax.to) provide dedicated fax numbers that work entirely over the internet. No landline, no fax machine, and no dedicated phone line are required. Faxes are delivered as PDFs to your email or app inbox.
What happens when you call a fax number from a regular phone?
You hear a high-pitched tone — the fax machine's CED tone (2100 Hz). This is the receiving device signaling that it is ready for a fax transmission. Since your phone does not emit the matching CNG fax tone in reply, no handshake is established and the call ends within 30–60 seconds.
Can I use my cell phone number as a fax number?
Not directly. Cellular networks use digital protocols that are incompatible with traditional fax signaling. However, fax apps like mFax assign you a separate virtual fax number. Your cell number is used to log into the app; the fax number itself is a cloud-based number independent of your cell line.