And verizon uses what?
Verizon uses CDMA 2000 1x and EV-DO (some others for other services as well). Code Division Multiple Access (CDMA) technology originated from military applications and cryptography, and to date, do not have any report of highjacking or eavesdropping on a CDMA call in a commercially deployed network.
CDMA air interface is inherently secure and is clearly superior to first-generation analog and Time Division Multiple Access (TDMA) systems. The inherent security of CDMA air interface comes from spread spectrum technology and the use of Walsh codes. CDMA utilizes specific spreading sequences and pseudo-random codes for the forward link (i.e. the path from the base station to the mobile) and on the reverse link (i.e. the path from the mobile to the base station). These spreading techniques are used to form unique code channels for individual users in both directions of the
communication channel. Because the signals of all calls in a coverage area are spread over the entire bandwidth, it creates a noise-like appearance to other mobiles or detectors in the network as a form of disguise, making the signal of any one call difficult to distinguish and decode.
CDMA also has a unique soft handoff capability that allows a mobile to connect to as many as six radios in the network, each with its own Walsh code. This means that someone attempting to eavesdrop on a subscriberâ€™s call has to have several devices connected at exactly the same time in an attempt to synchronize with the intended signal. In addition, CDMA employs a fast power control, 800 times per second, to maintain its radio link. It is difficult for a third party to have a stable link for interception of a CDMA voice channel, even with a full knowledge of a Walsh code. Synchronization is critical, as without this synchronization, the listener only hears noise.
For CDMA 1xEV-DO, the high speed data technology, the forward link utilizes rate control instead of power control and time division multiplexing instead of spreading codes. However, it still has inherent security that
protects the identity of users and makes interception very difficult. In addition, the Media Access Control Identification (MACID) assigned to users is encrypted. User packets are assigned variable time slots and the data rate is controlled by the access terminal based on radio conditions. Packets are divided into sub-packets using Hybrid Automatic Repeat Request (HARQ) and early termination mechanisms. These attributes makes it virtually impossible to identify the user or correlate user packets. 1xEV-DO standard specification supports a security protocol layer ready for implementation of future security protocols.
That secures the wireless side of the CDMA, then they have additional layered defenses on other parts, but in short it's pretty safe.