When you talk on a mobile phone, a continuous connection to a channel is reserved for you on the GSM network, which means nobody else can use that channel. With EDGE, you can still have a continuous connection, but you only use the channel when you're sending data.

So, you might be connected to a channel all the time, but you only actually use it when you're sending data. One channel can be shared by many people. This is why you're billed for data transferred, not for time.

EDGE is significantly faster than than CSD (Circuit Switched Data, sometimes just called GSM Data). However, you may find transfers slower than maximum speed during peak hours in busy cell networks, because voice connections usually take precedence. As with GPRS, the data transfer rate also depends on your multislot class (see the GPRS section for details).

Pulses and bits

EDGE uses a slightly different technology than GPRS called 8PSK, or 8-Phase Shift Keying. Here's a very simplified explanation: data is sent over GPRS and EDGE in pulses. With GPRS, a pulse can carry 1 bit of data, but with EDGE, one pulse carries 3 bits. So it's not that the data actually moves faster, it's that more can be moved at any given time.

What if EDGE isn't covered?

In areas where an EDGE network is not available, connections will fall back on GPRS as a default.