Voice over internet protocol (Voice Over/P, Vo/P) is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications multimedia sessions over internet protocol (IP) networks, such as the internet. Other terms frequently encountered and often used synonymously with Vo/P are (P telephony. Internet telephony, Voice over broad band (VOBB), broadband telephony, and broadband phone.

Content telephone refers to communication services-voice, fax SMS and/or voice-messaging application – That are transported via the internet, rather than the public switched telephone network (PSTN). The steps involved in originating a VoIP telephone call are signiating and media channel setup, digitization of the analogy voice signal, encoding packitization, and transmission as internet protocol (IP) packet over a packetswitched network on the receiving side, similar steps (usually in the reverse order such as reception of the IP packets, decoding of the packets and digital-to-analog conversion reproduce the original voice stream. Even through IP Telephony and VOIP are terms that are used interchangeable, they are actually different IP telephone has to do with digital telephony system that use IP protocol for voice communication while VoIP is actually a subset of IP Telephony. VoIP is a technology used by IP Telephony as a means of transporting phone calls.

VoIP systems employ session control protocols to control the setup and tear – down of calls as well as audio codes which encode speech allowing transmission over an IP network as digital audio via an audio stream. The codecs used is varied between different implementations of VoIP (and often a range of codecs are used). Some implementation rely on narrowband and compressed speech, which others support high fidelity stereo codecs.

VoIP is available on many smartphones and internet devices so event the users of portable devices that are not phones can still make calls or send SMS text messages over 3G or Wi-Fi.

VOWLAN (Voice Over Wireless LAN) is the use of a wireless broadband network according to the IEEE 802.11 standards for the purpose of vocal conversation. In essence, its VoIP over a Wi-Fi network. In most cases the Wi-Fi network and voice components supporting the voice system are privately owned.

VOWLAN can be conducted over any internet accessible device, including a laptop. PDA or the new VOWLAN units which look and function like DECT and cell phones. Just like for IP-DECT, the VOWLAN’S main advantages to consumers are cheaper local and international calls, free calls to other VOWLAN units and a simplified intergrated billing of both phone and internet service providers.

Although, VOWLAN and 3G have certain feature similarities, VOWLAN is different in the sense that it uses a wireless internet network (typically 802.11) rather than a cellular. Both VOWLAN and 3G are used in different ways, although with a femtocel the two can deliver similar service to users and can be considered alternatives.