As is known, a communication session execution in telecommunication systems consists of two basic stages. The first stage is the session initiation stage and the second is actually the communication stage. For better understanding of the SI technology it worth noting, that those stages differ from each other not only by their objectives but also by requirements to possible data transfer delays.
The conventional approach to a session initiation procedure now implemented in the Internet has its roots in the area of telephony. Following this approach, only calling user interacts with a telecommunication system that is responsible for establishment of a communication channel between the calling device and the destination device pointed out in a result of this interaction. A called user plays passive role under the conventional session initiation approach (Fig. 14). The approach considers that any access to a communication network is an activity of a calling user aimed to start the procedure of session initiation.
It is obvious that in this case, the main function of the system for session initiation is a parsing of an address entered by the calling user and thus an addressing system must be native to the telecommunication system and corresponding to its internal structure.
Fig. 14. Conventional approach to a session initiation.
SDA: source (S) and destination (D) technological (network-specific) addresses.
A Human-to-System interaction under the conventional approach to a session initiation may base only on addressing rules well known to the user while intended mainly to a telecommunication system allowing it to complete identification of the destination device owned by a called user.
Such addressing rules are always unambiguous and simple but they are suitable most of all for equipment not for human. Human overcomes inconveniences of addressing system by keeping auxiliary contact list records in memory of his or her terminal or client software. However, the convenience of auxiliary records achieved at the level of a user terminal is not available at the level of public contact data.
The SI technology introduces new approach to a session initiation that assumes participation of both calling and called users regardless of their different roles in a session initiation procedure. Each user accessing a network introduces a “message about the person” as well as a network access type: a call to other user or a readiness to receive a call (Fig. 15). This “message about the person” is a public SI address (public name) of the called user.
In this case, the basic functionality of a telecommunication system for a session initiation consists of:
- Identification of the technological (network-specific) address assigned to a user terminal or the specific number handling proxy application that controls a call procedure.
- Determination of message type (a call request or readiness to receive a call) and comparison of messages entered by calling and called user.
- Establishment of a data transmission channel between respective calling and called user terminals in case that compared messages are identical.
Fig. 15. SI approach to the session initiation.
S1 – technological (network-specific) address of User A, S2 – technological (network-specific) address of User B; N1…n – personal names defined by called user B; Nk – personal name of called user B specified by calling user A.
Under the SI conception, a transport network considers a technological address of the called user B as a source address (S2) of transmitted messages, not as a destination address (D). Both terminals of user A and B use an address of transport control equipment as a destination address (D). Thus in some cases of network organization a technological address of a terminal (D) may be just not needed for its configuration.
Following this approach to a session initiation, content, purpose and internal sense of messages entered by the user have no meaning to a telecommunication system (Fig. 16). Its main task is a comparison of digital signals received from users in search of identical one. These signals are public addresses and may result from digital transformation of any text, numbers, pictures, sounds and other information.
Fig. 16. Input of a call request and the message about readiness to receive a call into an infocommunication system.
Natural addressing is completely independent from addressing of network elements, their topology and even dynamically changing relationships. Thanks to this fact, a network may use any technological addressing that is suitable for machine processing and programmatic routing between network elements.
A telecommunication network uses its conventional means and technological addressing system to carry out the second stage of session execution that consists in connection establishment and traffic routing between terminals. There is no need for the user to have any idea about specification and meaning of network addressing used by a communication system.
More information about message forming and transmission rules of SI protocols you can find in a number of invention descriptions (Russia Patent #2257681, Bull. #21 iss. on 07/.27/2005; Ukraine Patent #72976, Bull. #5 iss. on 05/16/2005, International patent application WO 2006/112758, European patent application EP 1892937 A1 iss. on 02/27/2008, Bull. 2008/08). |
