The answe is often more complex and simpler than the question. A number of factors come into play including the speed down, and up as well as latency which is the time taken for information to move on your connection.
Many Internet connections are based on DSL or Cable. There are a lot of differences in those services and each one has distinct benefits. Some Internet connections are based on fiber. Most internet connections based on fiber will have similar upload an download speeds, and will likely have very low latency, and very reliable service.
If you are unsure if your service would be suitable for VoIP telephones, please contact us with as much information as you have on your service package. This could include the name of the service from your invoice, or even a speed test (https://www.speedtest.net/) will help.