Once you have a reliable fax service like Centralis Health’s hMessage or hFax, it seems like everything should run smoothly, right? However, the quality of the fax operations depends not only on the service itself but also on the audio quality of the phone line delivering the fax signal.
The Centralis Support team often encounters a familiar situation: a participant, frustrated with high Public Switched Telephone Network (PSTN) phone service costs, switches to a VoIP provider promising lower rates prior to joining Centralis Health. Initially, some faxes might work fine after the switch, but problems soon arise. This scenario can unfold in various ways, such as during a business move, when a new office phone system is installed, or after months or years of successful faxing suddenly facing issues. Regardless of the specifics, Voice-Over-IP (VoIP) services typically do not perform well with faxing, and here’s why.
VoIP relies on a customer’s internet connection rather than the PSTN. In contrast to the PSTN, which provides a dedicated and uninterrupted channel for calls, the internet functions differently.
Think of the PSTN as a network of interconnected water pipes where each connection has a fixed path, ensuring that water flows smoothly from one end to the other without interference. This is akin to how PSTN manages voice calls with a dedicated channel that remains unaffected by other traffic.
Now, imagine the internet as a similar network of water pipes but with a more complex setup. Here, water molecules (data packets) are labeled with their destination and routed by devices called “routers.” These routers must sort through vast amounts of data and may reroute packets if the initial path is congested. Sometimes, if the routers are overloaded, they might even drop packets. This scenario represents the internet’s handling of data, where packets might be delayed, lost, or arrive out of order.
In VoIP, this can lead to “jitter,” where small parts of the audio stream are missing or disordered. While humans might not always notice these disruptions, fax machines and modems struggle with jitter because every packet of audio data contains unique information essential for correct communication. Unlike human speech, where missing sounds can be filled in by our brains, fax machines and data modems require every packet to be complete. Missing packets can result in incomplete or garbled data, leading to failed fax transmissions.
If audio disruptions occur during a fax transmission, they might be interpreted as silence. In fax communication, which is half-duplex (one end sends while the other listens), unexpected silence can signal the end of the transmission. Without error correction mode (ECM), these disruptions can cause the fax to fail. Additionally, if the fax system lacks robust recovery procedures, even minor audio issues can lead to transmission failures.
For casual fax users, problems with line audio quality often manifest as black lines, streaks, incomplete pages, or missing parts of the fax image, particularly when ECM is not employed on noisy connections. And VoIP jitter is not the only source for audio problems for fax. Other problem sources can potentially be…
Call waiting service on the fax line. (The call waiting “beeps” will disrupt audio.)
DSL service on the fax line. (Even with a DSL filter the net effect of the DSL signal being added-to and subtracted-from the line results in audio quality degradation.)
PBX or other office phone system problems. (Not all office phone systems are designed and tested to support fax.)
Electrical interference on the fax line. (Electrical currents can be induced by some kinds of electrical equipment such as fluorescent light ballasts, power adapters, and generators.)
Poor wiring. (Phone line wiring that is not properly connected can go undetected by human ears.)
Other problems at the telephone company. (There is a lot that goes on there and a lot can go wrong.)
Maybe your telephone company or long-distance service provider uses VoIP even if you don’t. (They want to save on their costs, too.)
When troubleshooting fax communication issues, ensure you have all four components in place: reliable hardware, effective software, a high-quality fax line, and a responsive support team who cares about your faxes. With these elements working together, you can expect dependable fax operations.