Softphone - Learn the basics

Ozeki VoIP SIP SDK dramatically accelerates softphone development saving time and costs in this way. However, before jumping into the middle of softphone development, let's elaborate some basic terms related to this topic.

Introduction

Softphone is the short term for software phone that is originally the software model of a physical telephone device. However, in a lot of aspects it extends the traditional telephoning functionality with some other useful features like video phoning or conference calling.

The softphone is a program that is capable for Voice over IP communication with other softphone solutions or even with physical VoIP devices or traditional telephone sets. The communication type is limited to the used communication equipments.

Ozeki VoIP SDK provides magnificient technology for softphone application development. You can create a simple solution for voice calls, an extended softphone for video calls or even an advanced VoIP application for conference calls.

In the next sessions, you will get to know all the terms related to softphone technology and the proper definition of them. First of all, you need to know the two basic protocols.

Voice over IP protocol

Voice over Internet Protocol is a standard protocol that was originally defined for voice communications over the Internet. Today this protocol is extended for video communication and data transmission purposes, too. The protocol definition is set in some RFC (Request for Comments) documents that specify all the methods to use in the communication.

The steps involved in originating a VoIP telephone call are signaling and media channel setup, digitization of the analog voice signal, encoding, making packets, and transmission as Internet Protocol (IP) packets over a packet-switched network. On the receiver 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.

Ozeki VoIP SDK makes your work more efficient by providing full VoIP support for your applictions. If you want to know more about VoIP technology, you can read the related manual pages on our website.

Session Initiation Protocol

Voice over IP communication often uses the SIP protocol for establishing communication lines between the communicating parties. The main goal of this protocol is to create, modify and terminate communication sessions in between the end points.

Ozeki VoIP SDK saves you a great deal of effort by providig a full SIP protocol implementation. If you want to know more about the SIP protocol, please check the related manual site. If you want to know how you can use the SIP backgroun for a VoIP softphone application, you can start with an easy to learn softphone solution.

The next sections contain the basic definitions for softphone-related terms.

Phone line

The phone line or channel provides the infrastructure for the data that is transferred over the Internet. This term is the model for the physical telephone cables in the traditional telephoning systems.

The voice over IP communication is made of voice digitization, data transmission and decoding the audio data into analog voice on the other side. In this model all the data travels through the phone line as simple Internet packets.

Once the connection between two end-points has made, the communication is created for the two contacts. The softphones grant the possibility of more than one separate communication lines at the same time. You can communicate using multiple media types, such as Voice communication or Video messages.

Ozeki VoIP SDK provides revolutionary technology for even multiple phone line handling in your VoIP applications. If you want to know how easy you can use this extraordinary feature, check the developers guide article on this topic.

Phone call

The communication between two end points, regardless of technology background, is made through phone calls. A call is made through an established phone line or channel and basically means the actual data transmission and voice (and video) encoding and decoding processes.

The phone call starts with the dialing process as in case of traditional telephony, then the phone line is established through the SIP protocol and when both parties accepted the line establishment, they can start communicating. The call ends when one of the end points ends it.

Ozeki VoIP SDK provides magnificient technology for handling multiple simultaneous phone calls. If you want to learn how you can gain the best solution for this purpose, you can check the developers guide article on multiple phone call handling.

Codecs

Making an audio call needs some background support from the software and hardware solutions in use. The speech of the communicating parties is analog voice that needs to be encoded into digital audio data that can be transmitted through the phone line. When the audio data arrives to the remote communication party, it needs to be decoded back to analog voice information that can be played through a speaker or a telephone set. This coding and decoding process is done with the use of the so-called codecs.

The codecs are used for data coding and decoding, data encryption, conversion or suppression, too. These processes are essential for VoIP communication and they also affect the quality of the communication. VoIP communication originally requires the use of the same codecs on both communication end points, however, in some special cases the PBX can translate between codecs during the communication.

Ozeki VoIP SDK provides an extraordinary support for a great number of audio and video codecs. You can check the full list and features on the supported codecs page.
If you want to know how you can use the codec support and how you can change codecs in your VoIP application, check the developers guide manual page on this topic.

PBX

The Private Branch Exchange (PBX) is a software or hardware equipment that is responsible for establishing the phone line between the communicating parties. The communication software and hardware devices register to the PBX with a SIP account and the SIP protocol is also used for line establishment.

After the communication end points are registered, they can dial each other's number (SIP account). When the line is established between them, the PBX exits the communication and they switch to peer to peer connection. The PBX will have a role again at the end of the call when the session between the two end points needs to be closed.

Ozeki VoIP SDK provides professional technology for PBX development. You can learn here how you can implement a simple PBX solution or even an advanced PBX application.
If you want to know how you can connect a softphone to a PBX system, you can also find your answers.

Voice & video messages

The Voice over IP communication programs are useful when you are not available for actual communication. The softphone solutions can be easily extended with audio and video message sending and receiving functionalities that are not the part of traditional telephone sets.

The audio and video messages are handled similarly to simple communication. The phone line is established between the end points and the data transmission works in the same way. The only difference is that the communication is not done in real time.

How to build a softphone with Ozeki SIP SDK

Select an Ozeki SIP SDK license for building your softphone