Voice quality used to be very good on mobile. My first CDMA phone was indistinguishable from a landline, with some people surprised I was right outside their door when I called. And it was a big selling point in the early mobile analog to digital transition. My first cellphone was from Primeco PCS who made had no qualms about saying that TDMA (the competing standard at the time) sounded like shit compared to their CDMA phones.
As all good things eventually end Primeco was sliced up into Verizon Wireless and Sprint. With the only competing tech being TDMA from ATT Wireless they compressed the voice channel even more to accomodate more customers.
TL;DR: CDMA audio, currently, is almost indistinguishable from landlines but the carriers choose compression over quality
Quite true. On my old Verizon Motorola P8767 (a color flip phone -- it had four colors) I could enter "engineering mode" and increase the bitrate of voice calls over the network. It meant you were using more than your share of the voice pipe, but at least my voice sounded excellent.
Switching to a 2007 AT&T iPhone from Verizon was the equivalent of going back to two tin cans on a string. A string that a vengeful voice god would cut at random between 5 and 15 minutes every call.
Yes, was about to respond and say exactly this. The frequency response is something like 300-3500Hz (vs. 20Hz to 20kHz for normal human hearing), and the dynamic range is also pretty mediocre. Skype is much better, and many in-network cell calls that never touch POTS also have better call quality already than landline phones do.
Yes, now imagine a mobile phone system with quality that couldn't even match that. People can usually tell you are calling from a mobile based on the quality of the call.
Skype is great, until about 1800-2000h. Then the quality turns to crap as everyone comes home, does netflix, bittorrent, youtube, etc. and saturates the bandwidth. Unlike most offices, homes don't get a SLA.
You're absolutely right. They chose compression over quality to load as many concurrent calls per tower (CDMA, mind you) as tolerable. It used to be (maybe still is) that on the Motorola Razr v3m you could drop into a programming menu, and force the handset to use the higher bitrate vocoder, whereas the towers would request use of the lower bitrate vocoder. Around Chicago, in 2000, for example, Sprint CDMA was indistinguishable from a landline, likely because the towers were telling handsets to encode with the high bitrate.
As all good things eventually end Primeco was sliced up into Verizon Wireless and Sprint. With the only competing tech being TDMA from ATT Wireless they compressed the voice channel even more to accomodate more customers.
TL;DR: CDMA audio, currently, is almost indistinguishable from landlines but the carriers choose compression over quality