Functionally, both VoIP and traditional telephony offer the same basic set of capabilities, however through distinctly different core infrastructure. Both technologies have their own sets of advantages and disadvantages which this section will highlight alongside the main differences that a basic VoIP solution offers in comparison to the traditional landline.

Connection differences

Traditional telephones transmit voice communications over electronic signals through centralised public telephone exchanges. The call connection is generally dedicated for the duration of the call. With VoIP, the fundamental difference is that the connection resides over a packet-switched network (such as the Internet or a private LAN), as opposed to a circuit-switched network (such as PSTN).

While Internet connections generally utilise the telephone network, there exist a multitude of other available connection means, such as cable and wireless Internet. Software based VoIP and some hardware VoIP solutions use typical Internet infrastructure as a transport layer. Managed VoIP services offered by companies such as Cisco may utilise an IP infrastructure separate to the Internet which offer higher quality of service and security than other Internet-based VoIP services, for additional costs.  With VoIP, voice communications are transmitted in the same way as data communications, such as when you send an email or view a web page.

In traditional telephony, phone calls may be shared with other telephone line based services (e.g. DSL Internet), however these phone calls will have dedicated frequencies which guarantee phone call accessibility. VoIP phone calls also share a connection (an IP connection) however VoIP calls may not have guaranteed connection use. At a technical level, VoIP conversations are broken down into “IP packets” (small blocks of data) and these packets are sent separately via potentially different journeys across the network, which may include the Internet.  This approach is noticeably different to the single continuous transmission circuit provided by traditional telephones.