Faxing with VoIP can be slightly different than the traditional Public Switched Telephone Network (PSTN). Not all VoIP providers offer Fax capabilities and some charge extra for this feature. Some VoIP adapters or ATA-s as they are called allow fax capabilities by simply connecting your fax to the device. Faxing with VoIP can be slightly different than the traditional Public Switched Telephone Network (PSTN). Not all VoIP providers offer Fax capabilities and some charge extra for this feature. Some VoIP adapters or ATA-s as they are called allow fax capabilities by simply connecting your fax to the device. If your ATA supports fax capabilities you should not need a second line to send faxes. Beware that unusual amounts of faxing can violate your Terms of Service agreement with some providers and force you to upgrade to their business service, I think the normal user should not have a problem with this. Some providers require you to purchase a second number for your faxing needs and charge a minimal amount for that service usually around $ 5 or $ 10 per month.

VoIP Provider Fax Information: