The term “bandwidth” just refers to the size of the “pipe” available for transmitting signals. And it’s been a while since voice calls were transmitted as analog signals. They use digital systems for everything but the “last mile” of the network. Everything goes over the same network links, though various signals are separated out logically through different headers attached to the data packets. Here’s an explanation of voice calls from Wikipedia:
As described above, most automated telephone exchanges now use digital switching rather than mechanical or analog switching. The trunks connecting the exchanges are also digital, called circuits or channels. However analog two-wire circuits are still used to connect the last mile from the exchange to the telephone in the home (also called the local loop). To carry a typical phone call from a calling party to a called party, the analog audio signal is digitized at an 8 kHz sample rate using 8-bit pulse code modulation (PCM). The call is then transmitted from one end to another via telephone exchanges. The call is switched using a call set up protocol (usually ISUP) between the telephone exchanges under an overall routing strategy.
The call is carried over the PSTN using a 64 kbit/s channel, originally designed by Bell Labs. The name given to this channel is Digital Signal 0 (DS0). The DS0 circuit is the basic granularity of circuit switching in a telephone exchange. A DS0 is also known as a timeslot because DS0s are aggregated in time-division multiplexing (TDM) equipment to form higher capacity communication links.
A Digital Signal 1 (DS1) circuit carries 24 DS0s on a North American or Japanese T-carrier (T1) line, or 32 DS0s (30 for calls plus two for framing and signaling) on an E-carrier (E1) line used in most other countries. In modern networks, the multiplexing function is moved as close to the end user as possible, usually into cabinets at the roadside in residential areas, or into large business premises.
These aggregated circuits are conveyed from the initial multiplexer to the exchange over a set of equipment collectively known as the access network. The access network and inter-exchange transport use synchronous optical transmission, for example, SONET and Synchronous Digital Hierarchy (SDH) technologies, although some parts still use the older PDH technology.
Within the access network, there are a number of reference points defined. Most of these are of interest mainly to ISDN but one – the V reference point – is of more general interest. This is the reference point between a primary multiplexer and an exchange. The protocols at this reference point were standardized in ETSI areas as the V5 interface.
Even today’s voice communications are transmitted on a separate “pipe” than data, as VZW’s voice is over its 1xRTT network, and most data is over its EvDO Rev A or LTE networks. Yes, spectrum is a concern, but how much when they are functionally separate? As you said, 1xRTT is digital, not analog, but they still aren’t IP packets on even the same network from what I understand.
This article makes it sound like “the tubes are clogged,” which is ridiculous (unless you are on at&t).