Most SAT's used for Internet connections are geosynchronous. This means that their orbit period is the same as the length of a day, so they are stationary in relationship to a given point on the ground. To achieve such an orbit, the SAT must be 22,235 miles (35,784 km) above the earth's surface. Radio waves travel at the speed of light, but even the speed of light takes a noticeable amount of time to travel that distance 4 times (up and back twice for a complete round trip from your Voicebox to our servers.) This delay, when added to other factors on the ground, can cause delays anywhere from 500 ms to 1000 ms (1/2 second to 1 second.) It can be very difficult to carry on a conversation when there is that much delay.

Probably more important than RTT Delay itself is the consistency (or lack of) of the RTT Delay. Some packets take longer than others to reach their destination which can cause voice data to arrive out of order and possibly be dropped. We have found that many SAT Internet connections have this failing. Our voicebox does have adaptive Jitter Buffers, which can absorb some small inconsistencies in RTT delay, but given large inconsistencies, the result is often an almost unusable connection.

Typically SAT Internet connections are asymmetrical with their download bandwidth being much higher than their upload bandwidth . If your uplink bandwidth is lower than the bandwidth required by the vocal codec you are using then you will not be able to use the connection for voice calls reliably.