BT AMBASSADOR ESS

User Guide
Ambassador and Senator Telephones
Customer Apparatus Notes

Sales Brochure - PHME811

Ambassador was originally known by it's development name of "Electronic Plan System (EPS)".  The Ambassador ESS (AESS) is a microprocessor controlled switching system produced in two different sizes, AESS 1+3 (1 exchange line and up to 3 extensions) and AESS 2+4 (up to 2 exchange lines and up to 4 extensions).  Both types can have AESS 1 or AESS 2 software, later production AESS 2+4 with Mk 2 hardware has AESS 2 software only.  All AESS central control units (CCU) are externally similar but the 2+4 CCU is larger than 1+3.  All AESS systems with AESS 2 software were marketed as 'AESS 2'.

There are 2 intercom circuits on both versions.

Approved for LD & MF to exchange. Signalling determined by terminal.

The equipment comprises a wall mounted central control unit (CCU), Ambassador Adapters providing external (2-wire) extension, inter-PBX and extension bell facilities are also available.  The external extension and mains powered bell-adapters may be used on any AESS but LJU bell-adapters and IPBX adapters are only for use with AESS 2+4 systems.

AESS Terminals 852x & 855x only signal in 10pps LD and Telephones No. 8530 only signal in MF4. AESS Telephones No. 8560 & 8561 support both LD & MF signalling and can provide Timed Break recall to host systems (by customer accessible switches on the base of the telephone).  The Autodial No. 5000 (factory modified Tyne Callmaker) was also introduced for use with AESS terminals to provide 50 address autodial facilities.

Ambassador ESS 1+3 no longer available for new supply from BT on 1st September 1987.
Ambassador ESS 2+4 no longer available for new supply from BT on 31st July 1991.

These systems and telephones were made originally by GEC, then GPT Ltd who became part of Siemens.

FACILITIES AND FEATURES

The following is a list of approved facilities which are fully described in the extension users guide:-

• Push button dialling (MF or SC)

• Intercom calls

• Push button selection of exchange lines

• Exchange line status indication at each telephone

• Direct connection to exchange lines on mains failure

• Hold

• Enquiry during internal or external calls

• Transfer

• Divert

• PBX recall

• Secrecy on intercom and exchange lines

• Secretarial overide of divert with message waiting indication at diverting extension

• Extension programmable exchange line ringing Click tone to indicate incoming calls, introduced on intercom circuits under certain conditions

• Conference between an exchange line and two extensions

• Ring back on hold

• Wait on busy

• Call identification by differing ringing cadences

EXTERNAL EXTENSION FACILITIES

Two wire external extensions may be provided in place of the dedicated terminals using the External Extension adaptor SA10253.  Each two wire extension requires a separate adaptor, which is wall mounted adjacent to the CCU.

The facilities of an external extension are similar to those above, with the following exceptions:-

• Selection of any spare line by dialling 9.

• Selection of a particular exchange line by dialling 81 or 82.

• Remote answering of exchange calls.

External extensions can not initiate diverts, or be a party on a conference.  Calls which have been transferred to an external extension can not be transferred again to another extension.  No visual indications are given.

1 + 3 CCU

APPROVAL STATUS
Approved for:-
Direct connection to the PSTN (using 10 pps loop disconnect pulsing or MF4 signalling).
Indirect connection via Inter-PBX circuits as per PXML or by working as a (List A) subsidiary system (using 10 pps loop disconnect pulsing or MF4 signalling) connected to a (List C).

Ambassador ESS systems can provide earth-loop recall or 'C wire supervisory' signals to host system.

SOFTWARE: The following software levels (as marked on plug in processor IC) are approved for use with AESS:-
MP1197 - AESS 1+3 - Mark I units.
MP1198 - AESS 2+4 - Mark I units.
MP1199 - AESS 2 (1+3) and AESS 2 (2+4) - Mark II units.

Central control units, extension bell adapters (SA 10255) and Autodial 5000 require 240 Volts, 3 Amp, 50 Hertz mains supply.

The extension bell adapter SA 10255 has been superseded by a non mains powered unit known as "LJU bell adapter for AESS" Item Code 870216 (not for use on AESS 1+3 systems).

AESS 1+3 systems have a nominal power consumption of 40 watts whilst AESS 2+4 systems have a nominal power consumption of 150 watts.

System operation may be affected if the mains supply to the control unit is subjected to interference from other electrical equipment on the same circuit.

INSTALLATION
In accordance with Installation Guide and PXML No. 80 supplied with the CCU except that in accordance with BT practice ALL six wires are connected at the LJU, (the green/white and white/green wires being left suitably insulated at the CCU end for future use).

Extension Line Limit:-
Dedicated terminals - 250 ohms
Two wire - 1250 ohms (via two wire adaptors)

These limits are not in addition to the normal exchange signalling limits.  The total resistance from the exchange to each extension must not exceed the limit of the exchange.

Extension user programmable facilities include:-

• Exchange line ringing

• Divert

• Stored number (10 address Telephones)

EXTENSION WIRING

MAIN PARTS

The adapters are identical to Senator adapters and apart from IPBX adapter share the same Item Codes.  The IPBX adapter has a different Item Code to the Senator IPBX adapter so that it may be supplied without the modified Senator extension card.

EXTERNAL EXTENSION ADAPTOR - WIRING

EXTENSION BELL ADAPTERS - WIRING

NOTE: When fitting ring Generators & bell Adapters:-

1. Telephones 8520/8530/852 1, will need a 6 way cord 6/500 (BT Item Code 512231).

2. Also check that the "safety pin" switch "link A" is OPEN.

3. Telephones 8550/8551/8552 come with a 6 way cord.  Also check that the "safety pin" switch "SW 1 " is OPEN.

4. Telephones 8560 and 8561 come with a 6 way cord and do not have switch settings to change.

Ringing Generator 2A (IC 375507)
A maximum of 6 high impedance bells can be connected in parallel across OUTPUT terminals "High" and "LOW" in the Ringing generator.

The INPUT terminal DC+ is connected to LJU terminal 6.
The INPUT terminal DC-/AC Com is connected to LJU terminal 4.

Fuses
The fuses used on this system are BT types:- 72/0.5, 72/1, 73/1 & 73/2.

Last revised: December 09, 2023