Using a fax machine connected to VoIP often ends in frustration with many failed transmissions. For occasional faxing, initiating a few straightforward changes to the fax machine's settings, as well as using the proper VoIP codec, can improve your success. With these settings relatively stable faxing over VoIP can be accomplished.
Businesses that depend on faxing, including those companies that transmit and receive multipage documents, a traditional fax connected to copper phone line or a virtual fax service is essential.
Some VoIP services use a compressed codec which will cause fax transmissions to fail. Additionally, a few services offer a "fax" setting which forces the connection to use G711. If you discover a setting "bandwidth saver" it should not be enabled.
Faxing over a VoIP connection has improved over years, but businesses that do more than an occasional fax should remain with a traditional PSTN fax line rather than fax over VoIP. We find that in regulated corporations like insurance, healthcare, financial services, legal and real-estate, fax remains an essential requirement. However, some excellent virtual fax service providers are modest in cost and offer exceptional applications. Perhaps the ideal solution is to switch to a reliable cloud-based fax service.