End-to-end voice and data traffic over cellular networks is a challenge for service providers. The traditional circuit-switched voice network is not well-suited for the packet-switched data network, and the two networks have different performance requirements. In addition, the voice network is more sensitive to delay and jitter than the data network.
A voice call consists of a series of packets that are transmitted over the network in a real-time stream. The packets must arrive at the destination in the correct order and at the correct time. If the packets are delayed or arrive out of order, the call quality will be degraded.
The traditional voice network is a circuit-switched network. A circuit is established between the two endpoints and the voice traffic is transmitted over the circuit. The circuit-switched network is not well-suited for the packet-switched data network. The data network is a best-effort network, and the packets are not guaranteed to arrive at the destination in the correct order or at the correct time.
In addition, the voice network is more sensitive to delay and jitter than the data network. Delay is the time it takes for a packet to travel from the source to the destination. Jitter is the variation in the delay time for a series of packets. The voice network requires a low delay and low jitter to maintain good call quality. The data network does not require a low delay or low jitter.
Service providers are looking for ways to combine the voice and data networks into a single network that can meet the performance requirements of both networks. One approach is to use a voice over IP (VoIP) gateway to convert the voice traffic to packets and transmit the packets over the data network. The VoIP gateway will add delay and jitter to the voice traffic, but the call quality will be better than if the voice traffic is transmitted over the circuit-switched network.
Another approach is to use a voice over LTE (VoLTE) gateway to transmit the voice traffic over the LTE network. The VoLTE gateway will add delay and jitter to the voice traffic, but the call quality will be better than if the voice traffic is transmitted over the circuit-switched network.
The voice network is still needed to provide service to the legacy phones that are not compatible with the VoIP or VoLTE gateways. The voice network can be used
