There are multiple conditional answers. For features and functions, wireless duplicates and enhances the telephone experience. Economically, wireless can compete with the PSTN. However, geographic coverage is better, at this time, with the PSTN. The biggest issue is the legislative and regulatory requirements for the PSTN that are not matched by wireless networks. The Carrier of Last Resort (COLR) is a PSTN requirement that is not met by the wireless networks.Geographic Coverage The multiple wireless networks in the US provide varying service in many geographic locations but they are not ubiquitous. There are many locations that are not served. Look at the Verizon and AT&T maps you have seen in television ads about the national 3G coverage. AT&T has considerable empty space. Even though Verizon's coverage is broader, there are still many empty spaces on their map. There is no COLR for wireless, therefore there is no guarantee that all locations in the US will be served. Without a COLR for wireless, the wireless carriers will not serve those customers that produce low revenue, or the wireless carriers will have to charge premium rates to serve these customers.
The 2G, 2.5G and 3G data services can all carry voice calls successfully in their territories. VoIP over wireless can operate without significantly taxing the bandwidth of the wireless data networks. Voice call quality over wireless VoIP may be a problem because of the long latency of wireless, 100ms to 200ms and the increased packet loss. Latency will be reduced as the wireless carriers move to 4G and LTE technologies. Packet loss will still be a problem. Therefore it is unlikely that wireless VoIP will soon dominate and cause the legacy wireless voice services to be terminated.
Independent of which method is used for wireless voice communications, wireless voice or VoIP, the wireless carriers depend heavily on the PSTN for interconnection. I asked Mike Finneran, a NoJitter blogger who focuses on wireless technologies and issues, about the use of the PSTN for wireless interconnection. He said, "The wireless carriers depend on the PSTN as much as the VoIP providers do. Their peering connections are virtually all through the PSTN. They don't talk to each other, much less provide direct trunking--and why would they? Wireless as a carrier of last resort? That's like buying Tequila shots for the designated driver!!!"
Mike also pointed out that the power backup for cell sites is for hours, not days. When a cell tower losses power, the carrier can drive a mobile backup generator to that site. But if many sites lose power as in Katrina, the carriers do not have enough backup generators for a large number of power-failed sites. The wireless carrier's MSC (mobile switching center) does have backup generators, but these may be useless if the towers' power fails. Will the wireless carriers invest in improving their power backup to match that of the PSTN? Only if required. Think about 911 calls if there is no PSTN and the cell towers lose power.
The Carrier of Last Resort (COLR) Issue Historically, the US has committed to ensure that all citizens have access to a local wireline telephone exchange for Plain Old Telephone Service (POTS). States have helped achieve this commitment by enacting their COLR policies. The policies can be enacted by state legislatures and/or state commissions. The COLR policies impose a financial burden on the Incumbent Local Exchange Carriers (ILEC). The result of these COLR policies is the delivery of a network that provides nearly all residents the opportunity to subscribe to a reliable and high-quality wired voice service without any discriminatory terms. The federal and state regulators assigned the COLRs carrier to carrier responsibilities that produced a fully interconnected network so that any caller could connect to any other caller.
As COLRs, AT&T, Verizon, Qwest, Fairpoint, Frontier and smaller ILECs have to provide the PSTN services in their coverage areas. A COLR is any Telecommunications carrier that has to provide service to any party that has the ability to pay. The term is codified in the Federal Communications Act of 1996, 47 U.S.C. 214 (e).
COLRs do not necessarily make a profit when providing telephone network access. This is compensated by allowing a monopoly franchise within the state. The state commission sets the rates so that a reasonable return on investment was achieved for the COLR. The states also have the jurisdiction to allow or prevent a COLR from abandoning the franchise or selling the network investment to another carrier. The rate designs were created to allow large financial contributions to the common costs for certain classes of customer; businesses paid more than residents for the same service. The federal policies, from the Communications Act of 1996, authorized the FCC to pay universal service support to multiple carriers including non-COLRs. The universal service support was designed to provide additional revenue for the COLR so that it could provide POTS.
If there is no COLR, should there be a Universal Service Fund (USF)? The USF is primarily used to support the COLR where the delivery of voice service is not profitable. The USF is also used to improve Internet access and educational communications. Will there then be a USF charges for wireless and broadband services? Should there be a USF to extend broadband and wireless access? I don't have a conclusion but I think the USF question has to be answered in concert with the closure of the PSTN and the change or termination of the COLR policies.
