BT OCTARA 32 and 32X

APPROVAL No. NS/1209/3/F/600049

Time and Date change

The Merlin Phone System is a stored program control (SPC) key telephone system utilising micro-processing control techniques with time division multiplex (TDM) switching and digital (A-law PCM) speech transmission between the Key Service Unit and the Keystations.

The Octara 32 has a maximum configuration of 10 public exchange lines and 32 extensions, and a minimum configuration of 2 public exchange lines and 6 extensions. The system has dedicated keystations which have up to 20 feature keys supported by LED indications in order to present the system feature capability to the user. A less sophisticated key station is also available, and this provides similar access to the Keysystem features via a 12 key standard push-button telephone key-pad.

The Octara 32X can also provide up to 8 private circuits, with a corresponding reduction in public exchange line capacity.

This system is also approved for use in the Simple Call Routing Mode (SCRM).

The Key Service Unit (KSU) is a self-contained wall-mounted equipment with a mains derived power supply unit, a main dis­tribution frame (MDF) and all switching and control elements.

Power-fail fall-back facilities are provided by suitable approved telephones to allow direct connection to the PSTN.

The apparatus must be connected to the PSTN, host CRA and analogue private circuits by the connection of incoming PTO cables to the Test Jack Frame.


Maximum System Capacities No.
Private Circuits 8) Total 10
Public Exchange Lines 10) Total 10
Extensions 32
Power-fail connections 6
Maximum KSU Module Capacities
Power supply unit 1
Base card (2 exchange lines 6 extensions)  1
Extension card (2 exchange lines 6 extensions) 3
Extension card (2 exchange lines 8 extensions) 1
Private circuit card (2 private circuits 6 extensions) 4

NOTE:  The Base card has both exchange line circuits provided with power-fail capability.

Each Extension card has one exchange line circuit provided with power-fail capability.

Simple Call Routing Mode
At least one TX23 or TX25 keystation must be connected to each installed system.  Where the number of exchange lines exceeds the number of TX23 or TX25 keystations, then each terminating station must be presented with every exchange line available at that station, with at least an audible indication.

Taken from the PXML

BT information

Octara 32/32X (was also known as S2031) is a key telephone system with a maximum capacity of 10 Exchange lines and 32 telephone terminals. Octara 32X has replaced Octara 32 for new installation work. It has a wall mounted central control unit with an integral box connection. There are three types of telephone terminals, a basic terminal (TX21), a Featurephone (TX23) and a Featurephone with full handsfree facilities (TX25).

Octara 32X can provide up to 8 private circuits with a corresponding reduction in exchange line capacity.

Note: If a private circuit is fitted in position 5 there will also be a reduction of 2 extensions.

Made by GEC Plessey Telecommunications Ltd

Approved for direct connection to the PSTN loop disconnect or MF signalling or by working as a (List A) subsidiary system (loop disconnect or MF signalling) connected to a (List C) PBX. The system will support either Earth or Time Break Recall.

The following software levels are approved for use with Octara 32:
Release 1.7, Release 1.8 and Release 1.9
The software is provided on two EPROM's on the Baseboard 1A and can be identified by the EPROM labels as follows:-

IC10    IC11   DKS L1 IG10   DKS L2 ICll   1/16399/7171   1/16399/l72  Release 1.7    
VER 1.7   VER 1.7  Release 1.8   VER 1.8  VER 1.8  Release 1.9    VER 1.9         VER 1.9

The following software levels are approved for use with Octara 32X:  Release 2.5, Release 2.6, Release 2.7 & Release 2.8
The software is provided on three EPROM's on the Baseboard 2A and can be identified by the EPROM labels as follows:

IC10    IC11   IC13   BT OCTARA 32XL  BT OCTARA 32XL   BT OCTARA 32XL    BG515 PT1 IC10       
BG515 PT2 IC11     BG515 PT3 IC13Release 2.5      DKS 6/3/87 V2.5     DKS 6/3/87 V2.5  
DKS 6/3/87 V2.5ReIease 2.6      DKS 27/11/87 V2.6   DKS 27/11/87 V2.6    
DKS 27/11/87 V2.6Release 2.7 DKS 27/10/88 V2.7   DKS 27/10/88 V2.7    
DKS 27/10/88 V2.7Release 2.8   DKS 8/5/89 V2.8     DKS 8/5/89 V2.8      DKS 8/5/89 V2.8

The following software level is approved for use with the Private Circuit Board - Release l.5
The software is provided on one EPROM and can be identified as follows:

 PC Firmware                         BG516 IC16                         DKS 6/3/87 V1.

The PXML specifically prohibited PSTN traffic over IPBX circuits or external extensions on Octara, but Oftel issued a Variation Order NS/V/123/100010 that allowed such use.


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Last revised: September 25, 2021