Many internet connections are based on so-called asymmetric DSL processes such as ADSL and VDSL. What makes these transmission technologies different from others is that their download speed is several times faster than the upload speed. For private internet connections where the main purpose is to retrieve a lot of data from the internet and little data is actually transferred to the internet, this transfer method is absolutely adequate. However, when providing professional applications and services using the internet connection, the upload and download speed should be about the same. This is because the data being retrieved from the server first needs to be transferred to the internet via the upload port before they can be transferred to the device on the user end via the download port.
In a cloud phone system the phone call is transmitted via the regular internet connection. A phone call generally requires the same transmission capacities in both directions. When using very few voice channels simultaneously, an asymmetric broadband internet connection will typically suffice. However, if the total bandwidth of the parallel connections exceeds the maximum capacity of the upload speed, there will be trouble during use, even with adequate download speeds. With respect to the speed of the internet connection for using cloud telephony, both upload and download speeds must therefore simultaneously be taken into account.