Knowledge Base - FlexFax: Fax-To-Email Fax Detection

Fax Detection is a low-cost option that allows occasional fax use on existing VoIP phone numbers. Ideal for experimentation, or for clients who may occasionally need to receive a fax, this service works by "listening" to the first few seconds of each incoming call. If it hears a fax tone, it switches to receive mode - if it does NOT hear a fax tone, it continues to ring the intended phone.

This process saves the cost of a dedicated fax phone number, but has limitations:

Faxes sent from some (often older machines) will fail.
Faxes sent will occasionally NOT be detected and you may receive a fax tone on your voice-mail. In this case, retrying often resolves the issue.
As the fax detection process is listening to the first few seconds of each call, this has the effect of adding to the caller's perceived delay in you answering the phone (e.g. a VoIP seat without fax detection rings 2 times to the caller and the recipient, but a VoIP seat with fax detection may be heard by the caller to ring 3 times while the receiving party only hears two rings). In short, the caller will hear one more ring than the recipient. This does not effect outgoing calls.
VoIP Fax-To-Email provides a method of delivering faxes direct to the intended recipient and can save paper from being wasted by printing unnecessary faxes.

For people who need Fax-To-Email with increased reliability, consider upgrading to a dedicated Fax-To-Email service with an independent phone number.