There is more than one kind of Digital Subscriber Line (DSL). Asymmetric Digital Subscriber Line (“DSL”: in general use, the “A” has been dropped in the acronym) is so called because upload and download speeds are not equal; Digital because the technology transforms a regular phone line to a digital connection.

Data is carried on a telephone line consisting of a twisted pair of copper wires. The wires are run from the customer premise to a telephone company Central Office DSLAM (Digital Subscriber Line Access Module), which may be many kilometers away from the customer. Both at the customer’s end and at the Central Office there is equipment that mixes together and splits apart signals based on frequency. The lowest frequencies are called “baseband” and carry traditional POTS (Plain Old Telephone Service) telephone service. Above baseband is placed the upstream channel, and above that at the highest frequencies is placed the downstream channel. At the customer end, the DSL signal is either split off using a device called a POTS Splitter placed between the wall jack and your telephone equipment to split the baseband signal apart from the DSL signals so that one connects to a phone and the other to an DSL modem or router, or the signal is carried over an DSL-only (“dry” or “naked”) copper line.

When a splitter is properly installed, DSL does not interrupt alarm systems, point of sale terminals, fax or phone calls and these services do not affect the quality of DSL.

DSL speeds are measured in Mega Bits Per Second (Mbps). One Mbps is one thousand Kilo Bits Per Second (Kbps). DSL services are distance dependent and are sold in BC and Alberta with download speed bands up to 150 Mbps. Upload speeds are up to 25 Mbps and are set depending on download service.

A long pair of copper wires is a difficult environment for a radio-frequency signal like DSL. Coax cable of the sort used for Cable TV has little signal loss over distance, and it’s easy to regenerate the signal with amplifiers along the way because each amplifier serves many subscribers at once. But telephone wires will attenuate (weaken) the signal strength quickly as the distance mounts, and it’s not practical to place many amplifiers along the path. Furthermore, the higher the signal frequency, the greater the attenuation. This means the longer the cable, the slower the maximum speed that can be achieved.

When the DSL modem or router first connects to the DSLAM unit at the telephone company, the two units perform a number of complex tests on the cable between them, and then negotiate exactly how they’ll talk to each other. Each unit collects stats on the signal heard from the other side and then sends hints back to inform the other side how it might adjust its transmission to better be heard. In this way they negotiate a “sync rate”, a maximum downstream and upstream speed which is both optimized and stable based on line conditions.

Achievable speeds depend on the attenuation of your phone line, measured in dB loss. The dB loss increases the further your location is from the serving DSLAM (Digital Subscriber Line Access Module).

• under 10dB, qualifies for 25 Mbps
• under 20dB, qualifies for 15 Mbps
• under 40dB, qualifies for 6 Mbps
• 40-60dB, qualifies for DSL, but service will be < 6 Mbps
• over 60dB, does NOT qualify for DSL

Please visit our Network: Speed Test for more information about measuring speed and to test the speed of your existing service. If your existing DSL service achieves less than 25 Mbps down or 5 Mbps up, contact us for currently available options.

No. DSL can be added to existing single business phone lines supplied by Telus, Allstream, Sprint, Shaw, Bell Canada, etc. The phone line used for DSL can be shared with an alarm system, point of sale terminal, modem, fax or voice calls because a splitter splits off a separate frequency for the DSL signal. You cannot use a line connecting to “Interconnect equipment” such as a telephone system, a PBX or a Key system. Many businesses, after converting to VoIP, use a remaining fax line.

Alternatively, you can add a line dedicated to DSL. “Dry” DSL is a copper line that cannot be used for regular telephone services. It is typically $5 or $10 a month, and is often installed to replace a more expensive business voice telephone line especially in cases when the office has entirely switched over to VoIP