SDSL / SHDSL

When we talk about standard internet connections, we are usually talking about Digital Subscriber Line (DSL) connections. DSL allows data to be transferred over existing wired telephone lines and is allocated to higher frequency bands to avoid conflicts with data from analog calls. 

The term DSL most commonly refers to Asynchronous Digital Subscriber Line (ADSL) technology. In this type of connection, more bandwidth is allocated for downloads from the internet service provider to the user, making downloads quicker than uploads. 

ADSL works like this because most users download more than they upload. In fact most common activities online, including web browsing and media streaming, only require a downstream data flow, making ADSL ideal for these use cases.
SDSL is different from ADSL in that bandwidth is split evenly between uploading and downloading flows.

SDSL is used for applications where data has to flow quickly in both directions. A classic use case is Voice-over-IP (VoIP) telephony. Here, large amounts of data are being constantly downloaded and uploaded as the callers speak to one another. Assuming that both callers talk the same amount, the same amount of data needs to be sent and received. 

By providing equal speeds for data uploads and downloads, and with connection speeds that are typically much faster than ADSL, SDSL connections can greatly improve the quality of VoIP calls. This technology is used in the leading VoIP solutions, including the NFON Cloud Telephone System. 

To find out more about analog and VoIP telephone technologies and to understand the capabilities of the NFON Cloud Telephone System, please review the articles below: