Voice over Internet Protocol . Mobile VoIP is the voice over IP protocol (VoIP) applied in mobile phones. This means that the voice signal that is transmitted in a communication between two mobile terminals, travels through the Internet using an IP protocol. With the latest advances in mobile telephony, it has been possible to make terminals powerful enough to allow an internet connection through wireless networks, with all that it entails: surfing the internet, sending and receiving e-mails, downloading different data files and use instant messaging applications either by text, voice or video. These last applications are the ones that allow sending and receiving voice packets that would be the basis of mobile VoIP.
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- 1 Wireless networks
- 2 protocols
- 3 Coding
- 4 Mobility
- 5 Delay
- 6 Advantages
- 7 Applications
- 8 Sources
To be able to speak via VoIP through a mobile terminal, it must be equipped with a processor powerful enough to allow a wireless connection to the Internet . Whether via Wi-Fi , HSDPA , WiMAX or EV-DO rev A, the latter is more specific for mobile telephony and the rev A variant of EVDO allows faster packet creation for both the uplink and downlink. .
The SIP signaling protocol is used to establish, modify and terminate connections between two users . Furthermore, it is capable of determining the location of the users, thus allowing more mobility. The SIP protocol is complemented by the RTP protocol , this is the one that transports the voice data packets, that is, the conversation that we send through our mobile terminal digitized and packaged using the IP protocol .
The voice must be digitized and encoded so that it can be sent over the IP protocol . Codecs such as G.711, G.722, G.723, G.728 or G.729 are used. These compress the audio data to use less bandwidth for streaming. In this way, many more connections are allowed on the same channel.
When a connection has been established between two users who may be on the move, they can change the coverage area of the base station that allows them to connect. When this happens, a new connection must be re-established with the new base station and it takes a certain time. The operation is similar to the handover used in conventional mobile telephony.
In addition to the delay introduced by changing the coverage area from one base station to another, there are others: Delays introduced by the processor when encoding, compressing and packing the data to send it through the IP network. Delays associated with the use of the IP protocol such as packet loss, erroneous packets sent, node queues full or network congestion.
The fact of using the IP protocol to communicate means a great reduction in the cost of calls, especially at an international level, since to have internet you only have to pay a fixed fee and this allows everyone to access where there are connections with the IP protocol .
It is anticipated that as this technology improves, more and more users will use mobile VoIP. The main reasons are that the call time does not increase the cost of the call and international calls can also be made for the same price.
Due to the large number of operations that the processor must carry out in order to make a connection via IP protocol , mobile terminals are required to be able to carry out this type of connection.
The smartphones are capable of performing the necessary operations and which are provided with increasingly powerful processors. VoIP transmissions through these types of mobile terminals have already been achieved through applications such as Skype for these.