DSL connections based on e.g. ADSL and VDSL, are asymmetric with different upload and download speeds. The download speed is typically a multiple of the upload speed. Since many applications primarily retrieve data from the internet and little data is actually transferred to the internet, asymmetric DSL connections are very common. However, these types of connection are inadequate for providing services via an internet connection. After all, in this case high upload speeds are required to transfer the information from the server over the internet and to the user. In this case, symmetric transmission technologies with equal download and upload speeds are a suitable solution.
Cloud telephony uses Voice over IP (VoIP) technology to transmit call information over the internet in form of data. Phone calls generally requires the same bandwidths in both directions of transmission. If only one or few phone calls are made at the same time, the upload speed an asymmetric DSL connection is typically still adequate. However, when there are a lot of simultaneous phone calls, the connection should be configured to provide adequate upload and download bandwidth.