The Consumer Report statement is WRONG. Enhanced 911 requires only that cellphone carriers provide some sort of radiolocation technology.
+"A second phase of Enhanced 911 service is to allow a wireless or mobile telephone to be located geographically using some form of radiolocation from the cellular network,
OR by using a Global Positioning System built into the phone itself.+
+Radiolocation in cellular telephony uses base stations. Most often, this is done through triangulation between radio towers. The location of the caller or handset can be determined several ways:+
+* Angle of arrival (AOA) requires at least two towers, locating the caller at the point where the lines along the angles from each tower intersect.+
+* Time difference of arrival (TDOA) works like GPS using multilateration, except that it is the networks that determine the time difference and therefore distance from each tower (as with seismometers).+
+* Location signature uses "fingerprinting" to store and recall patterns (such as multipath) which mobile phone signals are known to exhibit at different locations in each cell.+
+The first two depend on a line of sight, which can be difficult or impossible in mountainous terrain or around skyscrapers. Location signatures actually work better in these conditions however. *TDMA and GSM networks such as AT&T Wireless Services and T-Mobile use TDOA.*+
+CDMA networks tend to use handset-based radiolocation technologies, which are technically more similar to radionavigation. *GPS is one of those technologies*. Verizon Wireless and Sprint PCS use Assisted GPS."+
From the FCC website:
"Wireless carriers may comply with certain FCC E911 rules by ensuring that 95% of their customer's handsets are E911-capable *(also referred to as location-capable)*. The FCC’s E911 rules do not specify precisely how carriers may achieve this compliance."
http://www.fcc.gov/pshs/911/Welcome.html
