BusinessPhone Communication Platform 4.0
System Description ASB 150 02

## Examples

### Start of PBX

#### On installation (cold start)

A special "installation strap" is inserted in the front of the CPU-D_ board. This strap indicates that all semipermanent data shall be erased (E2PROM and battery backed-up RAM).

All processors in the system test their own boards. Faults (if any) on the device boards are indicated by yellow and green LEDs. During this phase the yellow LED on CPU-D_ glows steadily.

All device boards (RP) shall report to the CP, so that tables with the PBX's current configuration can be compiled in CP. All RPs report on what individuals the board is equipped with, which board position and how many individuals exist on the board. CP will then allocate memory space for all reported individuals. All devices (extensions, trunks etc.) are given default values for directory numbers, categories, etc. that are stored in CP's central database (E2). During this phase the yellow LEDs on CP and RP flash.

Thereafter, each central program block will initiate its boards/individuals by sending data to the device boards. During this phase CP's yellow LED will change to a steady glow while RP's yellow LED continues to flash until the relevant board is ready.

During the last sequence all central program blocks will receive information stating that the system is now ready to be made operational. During this phase CP's yellow LED will flash.

Thereafter the entire system is ready for traffic. All yellow LEDs are extinguished.

The installation strap must now be removed before the PBX is furnished with local (if any) alterations via system-programming. Otherwise all new data will be lost on system restart.

#### Normal restart (warm start)

The installation strap shall not be inserted.

Basically, the start sequence is identical to the one used for installation, except that the semipermanent memory is not erased and furnished with default data. Instead, all reported devices are checked against the stored database (E2) to verify that no boards are incorrectly situated.

### Traffic

#### Internal call

##### Call from "idle"

A digit key on a digital system telephone is pressed, which is discovered by the telephone's processor and this information is sent to the line board (ELU-D).

The information is analysed by the RP on ELU-D. Board position and individual number are added and a message is sent to CP stating that key X on the tele- phone that is connected to line board Y, individual number Z has been pressed.

This message is distributed within CP to the program block that administers telephones (EX).

The EX-program reads data for the telephone on board Y, individual Z and finds that the telephone had status= "IDLE". The received message is analysed with regard to this status. Memory is allocated and a process is created with status = "DIGIT RECEIPTION". Programmable parameters for the line are ordered from the common database (E2) and time monitoring (supervision) is ordered from the operating system.

An order is sent to the RP to light the LED for the key on the telephone on which the call shall be indicated.

At the same time information that telephone Y, Z is now in use is sent to all other line boards. Other telephones (if any) which have this telephone represented on a key will now have the LED for this key lit, as an indication that the telephone is busy.

##### Digit reception, analysis

Further key depressions are stored in the processor's temporary memory. The dialled number is analysed against all directory numbers that are stored in the PBX's common database.

When the dialled digits correspond to a known number, a seizure message is sent to the program unit that is responsible for the telephone or function that corresponds to the dialled number. In the message details relevant to own telephone line, number, categories, etc. are included.

Hereafter the party that dialled the number is called A‑party and the called party is called B-party.

##### Test

B-party's program unit analyses the received seizure message on the basis of data from A-party, own status (busy, free, etc.) and own data (categories) as well as available resources (PCM-channels etc.). If no restrictions exist, a process is created with status = "SEIZED" and an answer message "ok" is sent to A‑party.

##### Interconnection, ringing

A-party receives the "ok"-message, changes status and sends a message to B-party, which signifies start of the function represented by the dialled number.

For example, it is a call to another telephone, which means that the B-side will start ringing at own telephone, change status to "RINGING" and inform A-party that "ringing has started".

B-party will also inform all other line boards that its own telephone is "ringing".

A-party will, by means of the tone sender unit, order ring tone for own telephone.

The call is now controlled by two processes, one that administers A-side and another process that administers B-side. The PCM-channel is controlled mainly from B-side.

##### Answer

When B-party goes off-hook the line board's processor indicates that the telephone has gone off-hook. RP sends a message to CP. B-party's central process receives this message, and changes status to "SPEECH" and informs A-party accordingly.

##### Conversation

Both parties order the relevant line boards to connect the speech connection in the reserved PCM-channel. The time monitoring for the respective process is cancelled.

##### Disconnection

When one of the parties ends the conversation, e.g. by going on-hook, the relevant central process is informed of this. Then the connected party is informed that "we are now disconnecting". The connection between A- and B-parties is terminated. Each party administers its own line board, shuts off the connection to the PCM-bus and extinguishes LEDs (if any) on the telephones.

B-party returns the reserved PCM-channel to the central administrator so that it can be used for another call.

##### Idle

The processes are terminated, reserved memory is returned and status is set to "IDLE".

The parties will later inform all other line boards, individually, that their own telephones are free (so that the other telephones in the system that have the relevant telephones represented on a key, can update the LED-information).

#### External outgoing call

For an external outgoing call to the public network, the procedure is virtually identical to that for the internal call above. The difference is that B-party is administered by the central program block for external lines (TR) that communicates with device boards type BTU-...

Revision: K © Ericsson Enterprise 2003