Few things frustrate telephone users more than hearing an echo in the phone's earpiece, but this problem can arise from a number of sources. Traditional telephone service has evolved to include several echo-reducing safeguards, but modern telephony such as Voice over Internet Protocol, or VOIP, and mobile telephone services offer several opportunities for echoes to arise.
According to the wireless communication company Verizon, some telephones may actually produce their own echoes. On the company's Frequently Asked Questions web page, Verizon explains that users who hear an echo may have the volume turned up too high on the telephone handset. When the phone's earpiece plays a sound at high volume, the phone's microphone picks up the sound and re-transmits it. In such a case, both callers may experience an echo condition. To remedy this problem, Verizon recommends simply turning down the volume on one or both telephones.
Internet telephone users with VOIP phone service may hear an echo as the result of differences between the Internet and the public switched telephone network. According to the telephony website Adaptive Digital, telephone companies use a hybrid device to transition conversations between four-wire Internet connections and the two-wire PSTN. Among other purposes, this device serves the purpose of identifying and canceling echoes in the conversation. If the device does not work properly, or if the telephone company does not use a hybrid device capable of detecting and cancelling echoes, VOIP users may hear an echo during the conversation.
VOIP users may also experience echoes when they have poor Internet connections and during periods of Internet congestion. According to the Internet telephony organization VOIP Info, data packets carrying voice conversations may become misrouted when passed across a poor quality Internet connection. Some of these packets may become misrouted, lost or otherwise unable to reach their destination. As a result, the hybrid device that provides echo cancellation service cannot properly identify and resolve echo conditions. Similarly, network congestion can increase the time required for VOIP data packets to reach their destination and return to the sender, and this delay can cause the user to hear her own voice some time after speaking.
Though echoes can create difficulty for telephone users, VOIP Info points out that callers have become accustomed to hearing their own voices, as a form of echo, when they speak into a phone handset. This condition does not normally cause a distraction, though, as the echo occurs as the caller speaks; instead, the echo becomes troublesome when network or handset issues cause the sound to repeat some time after the caller speaks. In addition, traditional landline telephone companies rely on two-wire circuits to serve telephone connections, and these circuits typically facilitate conversations without creating echoes as long as the circuit maintains continuity and normal electrical impedance.