ADSL2 + uses a frequency range of up to 2.2 Mhz and can achieve download data rates up to 25 megabits per second and upload rates of up to 3.5 megabits per second. The maximum bandwidth is limited by many providers at 16 mgabits per second downstream and about one megabit per second upstream. In addition, many so-called rate-adaptive methods are used. The DSLAM and modem dynamically control the maximum transmission rate when making the DSL connection.

The key difference between ADSL2 and ADSL2+ is that ADSL2+ uses twice as much bandwidth along copper wires as ADSL2 does. ADSL2 uses exactly the same bandwidth as ADSL.

Usually, equipment in the exchange decides on the operating mode to use, with ADSL2+ giving the highest speeds (due to its wider bandwidth) although this makes it more susceptible to line problems. If reliable operation at the wider bandwidth is not possible, the exchange equipment may force operation using the ADSL2 mode. ADSL2+ is generally the preferred mode of operation for shorter distances (from the exchange) and ADSL2 is generally the preferred mode of operation for longer distances. If there is a line loss of over 55 dB (which corresponds to a distance from the exchange of about 4 km) will generally benefit from ADSL2+

The 'E' side represents the local loop connecting the telephone exchange to users has the capability of carrying frequencies well beyond the 3400 kHz upper limit of POTS - Plain old telephone service or plain ordinary telephone service for voice-grade telephone service employing analogue signal transmission over copper loops. Depending on the length and quality of the loop, the upper limit can be tens of megahertz. DSL takes advantage of this unused bandwidth of the local loop by creating 4312.5 Hz wide channels starting between 10 and 100 kHz, depending on how the system is configured. Standard ADSL over POTS uses the band from 26.075 kHz to 137.825 kHz for upstream communication and 138-1104 kHz is used for downstream communication. The higher frequency for downstream communication results in higher attenuation due to attenuation being a function of frequency.

Under the usual DMT scheme, each of these is further divided into smaller frequency channels of 4.3125 kHz. These frequency channels are sometimes termed bins. During initial training to optimise transmission quality and speed, the ADSL modem tests each of the bins to determine the signal-to-noise ratio at each bin's frequency.

Allocation of channels continues to higher frequencies (up to 1.1 MHz for ADSL) until new channels are deemed unusable. Each channel is evaluated for usability in much the same way an analogue modem would on a POTS connection. More usable channels equate to more available bandwidth, which is why distance and line quality are a factor (the higher frequencies used by DSL travel only short distances).

ADSL2+ provides most benefit for premises close to the exchange. For distances between 3 km and 3.5 km, where ADSL speeds have fallen well below 10Mbps, ADSL2+ and ADSL2 still provide worthwhile increases in connection speeds. There is very little difference in performance at distances above 4 km, as the table shows..