In recent times the communication service providers have shown increasing attention to speech transmission over networks. Such a technology is resource-saving due to both international and long-distance telephone calls expenditures reduction and easier deployment and support of voice data transmission networks. A variety of devices and software are being developed to digitize, compress and transmit voice in IP networks.
Internet telephony software/hardware developers usually implement the following basic approaches:
- Computer – IP network - computer
Two users of AMSD EasyTalk, separated by thousands of kilometers, can communicate in real time paying only for Internet connection. AMSD EasyTalk™ can be used in a local area network as well.
Since a computer is more universal device than a phone, it looks rather natural that subscribers can exchange text messages and send files to each other during the conversation. Besides, it is possible to communicate with several subscribers in turn (switching from one to another).
Early users of AMSD EasyTalk™ used headphones (or speakers) and microphones. Later special devices appeared, VoIP handsets, shaped like a regular phone receiver and connected to a sound card. So we can notice that, even by its external attributes, Internet telephony is getting closer to common telephony.
"Computer – IP network – computer" model is the simplest pattern for IP-telephony. It has a lot of benefits.
This configuration does not even require a telephone gateway since voice packages are digitized on the front end and sent over the network. The only weak point is package delays (or package loss) in the network. AMSD company has solved this problem with an optimized speech transmission protocol (AMSD EasyChannel™) which constantly tunes the process of package transfer depending on the communication channel quality.
- Telephone – gateway – IP-network – gateway - telephone
It may seem that calls from a telephone to another telephone with the help of AMSD TalkServer™ gateway have a very small difference from regular telephone calls. After registration at the telephone server the client dials the telephone number of the gateway, his identification number and then (after switching the phone into tone mode) the telephone number of his remote interlocutor. In this case, AMSD TalkServer™ will perform all the necessary checks and establish connection with a remote telephone gateway. If the remote telephone gateway provides the requested connection services, it connects with the remote interlocutor; thus, a remote network connection is established. It is remarkable that sound quality of Internet telephony is steadily approaching to the sound quality of common telephone lines.
- Computer – IP-network – gateway – telephone
If a client has installed AMSD EasyTalk at his computer and registered it at the server, he can call a regular phone from his computer via IP-network using AMSD TalkServer™ gateway. We remind here that the cost of Internet-telephony services is lower than the cost of traditional telephone connection.
- Telephone – gateway – IP-network - computer
A client can call a computer with AMSD EasyTalk installed after registration at the telephone gateway (the interlocutor should also have been registered in the gateway directory).
AMSD TalkServer software is provided with a VoiceCall feature which solves the problem of calling a dialup user at the moment when his telephone line is busy due to Internet connection. The initiator calls the telephone gateway, then the telephone gateway re-addresses the telephone call to the computer of the remote subscriber so that he can receive the call with his Internet phone without leaving the Internet session. In this case, if automatic number identification is turned on, the phone number of the incoming call will also be displayed.
Over six years ago AMSD company has started research and development in the field of IP telephony and released the first Russian IP telephone application, AMSD EasyTalk. By nowadays its AMSD EasyTalk 2.2RC version has been released.
Using Internet phones for long-distance and international communication "from a workstation to a workstation" has already become usual practice. Low costs of such communication and usually small Internet phone program price were widely appreciated. But human thought and technologies expansion have resulted in the idea that if it is possible to talk through Internet it would be even better to invent how to call from a phone to another phone using Internet. So there appeared an idea of a gateway, a hardware unit serving as an interface between a sound transmitting device (a computer or a phone) and Internet.
The gateway is also usable in a local network since it allows organizing office automatic telephone exchange based on IP-telephony enabling access to the municipal network through the gateway.
The next AMSD’s development was AMSD TalkServer™, a telephone gateway enabling link-up between a plain (FXO/FXS or E1) telephone line and an IP cloud.
The gateway provides voice and data sending/receiving, voice digitization and playback.
Strict compatibility between AMSD EasyTalk and AMSD TalkServer is provided, so that it’s possible to call both from a phone to a phone and from a phone to a computer where AMSD EasyTalk™ is installed through the gateway, and from AMSD EasyTalk™ to a regular phone as well.
In addition to the listed patterns AMSD company offers comprehensive practical solutions on Internet - telephony for local and global networks based on TCP/IP protocols for Microsoft Windows. As an illustration we'll give here some examples of AMSD Internet telephony products deployment:
Here is a pattern of a local IP-automatic telephone exchange on the base of AMSD EasyTalk with AMSD TalkServer™ gateway for accessing the municipal telephone network.
Such a pattern avoids the expenditures on purchasing an expensive office ATE and provides both access to a regular (municipal) phone from each computer equipped with AMSD EasyTalk and the possibility to receive a call from a municipal phone.
The following pattern is designed for Internet-telephony service providers, supplying "phone to phone", "computer to phone" and "phone to computer" connection types.
The development of Internet services allows Internet telephony providers to master a new area of communication industry. The keystone of success is the growing attention of citizens and organizations to long-distance and international telephone communication expenditures reduction and, as well, extended options (IVR, personal phone books) made available with Internet telephony.
This pattern shows how to build a network of local office (or IP-based) automatic telephone exchanges (ATE) linked to the municipal telephone network through AMSD TalkServer gateway.
- For Internet + local networks
1. Linking office ATEs into a network
Joining office automatic telephone exchanges into a virtual network is used to route the calls between two internal phones served by different remote office ATEs.
The connection between ATEs is carried out through Internet by AMSD TalkServer telephone gateway. The price of such calls is reduced to the price of Internet connection. If you assign a serial number to an office ATE in the gateway DataBase you may address it by this number calling from another office ATE; it will shorten the number dialed.
2. IP ATE network
À virtual network built of local IP-based ATEs is functionally similar to a virtual network of office ATEs; but it is implemented on the base of AMSD EasyTalk, allowing to avoid enormous expenditures on office automatic telephone exchanges. Connection between IP-based ATEs, as well as access to the municipal telephone system, is carried out through Internet by an AMSD TalkServer gateways. The system both provides access to telephone network from every computer equipped by AMSD EasyTalk and makes any computer equipped with AMSD EasyTalk available to external phone calls.
Each of the two listed patterns allows to connect branches and divisions of an organization located in different regions.
Corporate communication systems
Running conferences and transmitting various media "over IP" has become one of the most promising applications of Internet in recent times.
It is obvious now that voice transmission quality in voice-over-IP connections has, unexpectedly, achieved the quality of conventional telephony without any cost penalty. Quality VoIP today is still as economically attractive as "crude" VoIP five years ago.
A remarkable number of corporations with highly composite and distributed structure show growing interest in VoIP corporate communication systems (CCS), as introduction and application of such CCS allows to improve the organization of business communication without bothering about expensive office exchanges and switches (internal communication) or spending money on long-distance and international calls (interdivisional communication).
Voice-over-IP offers a simple approach to incorporate remote employees into the real-time everyday workflow, to personal and, as well, team communication, even to create the psychological effect of visual presence of co-workers or partners from remote regions and even continents.
Another important benefit of such systems is intra-corporate closure; information exchange is channelized and easily administerable according to the access rights hyerarchy among employees.
Let's observe the benefits of VoIP CCS in a more detailed way.
CCS have a significant difference from "conventional" Internet communication systems. Every e-mail, or ICQ, or NetMeeting user may connect to any e-mail, ICQ or NetMeeting user, respectively. Business communication inside a corporation implies a closed system, so that passers-by could not enter the controlled intercourse area.
Sometimes efficient workflow planning implies limited accessibility of certain groups employees to others. For instance, the top manager may initiate a conversation with any employee; but not every employee may initiace a call to the top manager.
Corporations have internal hyerarchy and division of labor. It is obvious that "availability teams" ("availability domains") framework should follow the hyerarchy, structural divisions and performed tasks. Usage of separate switches allows to discuss technical and business topics in customizable audience.
Access limitations imply access administration. Usage of particularized switches and software configuration tools allows to join IP ATE into a network of desired structure, components and availability rules. Every end-user application (IP telephone) can have access to one or more switches; every switch delivers availability
lists to its subscribers and provides connection to the requested one. Hardware separation of media streams (usage of more than one switch) allows to have a disconnected network graph, to improve conversation security.
- Deep transmission security
Internet connection in inter-divisional communications implies direct, host-to-host packet transmission, so that voice packets bypass the servers of Internet service providers. Direct packet transmission makes one more confidence benefit of VoIP corporate communication systems (CCS).
Only the simplest solutions are presented here. You can request a more complicated practical solution in the field of Internet telephony so that AMSD develop it according to your particular requirements.