Fax over VoIP

Sending and receiving faxes over VoIP is one of the technical difficulties that hasn't been completely solved yet. Although not as serious as emergency calls and power supplies during blackouts, a reliable method for sending faxes would help in the wider acceptance of VoIP.

The main difficulty is that faxes are a different kind of data than voice. Whereas voice data has to be delivered in real time in order to maintain a comfortable conversation, fax data can be delayed somewhat in order to guarantee that it is completely intact. It doesn't matter if some voice data is lost en route, but if this happens to fax data it creates an error in the fax transmission.

There have been many attempts to solve this problem -- some of them work some of the time but none of them work all the time. Methods like slowing down the speed of the data transmission or using a specific codec are used by some VoIP service providers. Users report partial success -- sometimes it works and sometimes it doesn't.

If you'd like to try sending faxes over your VoIP connection first of all make sure that your VoIP service provider supports this function. If so, they will probably give you instructions about how to modify the settings of your VoIP devices. You can probably start by setting the codec to 711u. Some people report that this is the only change they need to make to successfully send and receive faxes. Other people report that they must also lower the fax baud rate to 9600. There may be other fax settings that your VoIP service provider suggests.

All these settings may be hit or miss -- if you get the fax function to work, great! If not, and dependable fax service is important to you, you can either keep a dedicated PSTN line or use one of the many Internet fax services which are available. Efax allows you to send and receive faxes via e-mail. Some VoIP service providers may include this service as part of their package, and others may not provide it at all. You can still sign up with another company which specifically offers email fax.

Sending faxes via e-mail is a good solution. Computer documents can usually be sent without any intermediate step, but real paper documents need to be scanned into the computer before they are sent. The fax is sent as an e-mail attachment to the fax service, which forwards it to a real fax machine. The fax service company also provides you with a fax number where you can receive faxes. Any faxes sent to this number are converted to an e-mail attachment and sent to your preferred e-mail address.

You can subscribe for a relatively low monthly or yearly rate. Check out the various  Internet fax companies. Some allow you to send and receive an unlimited number faxes while other charge by number of pages. Having an idea of how many faxes you need to send allows you to select the most economical plan.