Question Which network has the best call quality to support sending faxes?

[Genralkidd]

I've tried sending faxes over VOIP connections before via my home landline (which is now digital) and it's really hit or miss. From my understanding that's because the call audio is compressed to too low of a bitrate. I was wondering if there's any cellular network out there with good enough call quality to potentially be used to send faxes over?

All the articles I could find about the topic are from the early 2000's with comparisons between 2G CDMA and GSM networks with most people agreeing that CDMA call quality was the best because it's analog. But fast forward to 2019 where CDMA networks are almost all dead... Is that still the case where CDMA has the best call quality for faxing even when compared to modern GSM or even VoLTE calls?

 

[BFG-9000]

The digital VOIP connection that works by far the best for faxing is cable internet with an ATA (Analog Telephony Adapter) VoIP Gateway that supports the T38 protocol. The fax is actually converted into a digital image inside the modem, then at the other end converted back to an analog fax either at the cable company or in the destination's own T38 modem.

Just about all cable telephony modems support T38 nowadays.

The only way to reliably send faxes over cellular is with one of those online fax services. You have to digitize the documents yourself and e-send them to the service, who actually uses an analog phone to fax it the rest of the way. Since you have to do all that, you could email them instead, but sometimes the receiver has no email

 

[Genralkidd]

The digital VOIP connection that works by far the best for faxing is cable internet with an ATA (Analog Telephony Adapter) VoIP Gateway that supports the T38 protocol. The fax is actually converted into a digital image inside the modem, then at the other end converted back to an analog fax either at the cable company or in the destination's own T38 modem.

Just about all cable telephony modems support T38 nowadays.

The only way to reliably send faxes over cellular is with one of those online fax services. You have to digitize the documents yourself and e-send them to the service, who actually uses an analog phone to fax it the rest of the way. Since you have to do all that, you could email them instead, but sometimes the receiver has no email

Is there no cellular network that has a better chance of working though? I remember in the early 2000's Sprint/Verizon's CDMA networks actually supported this kind of function and CDMA worked well because it was analog or something like that. But I don't know if that's still the case anymore in 2019.

 

[BFG-9000]

You sure used to be able to fax over 2G Sprint for a per-minute charge, and even receive faxes on your voicemail, then use your phone to forward them to any nearby fax machine number to print them.

However 2G has gotten really spotty, and Sprint is supposed to dismantle their entire CDMA system next year. Verizon is shutting down their CDMA system at the end of this year. Both AT&T and T-Mobile have already shut down GSM 2G for everything but things like utility meters and vending machines. And faxing has never worked with 3G or 4G. Their super-lossy bandwidth-saving compression of audio throws away enough of the fax tones that error-correction simply cannot compensate for it.

Scene from alternate future 2015 where faxing was more popular:

 

[hang-the-9]

Faxing 2019 style, take a picture, text the picture.