ANS & REC MACH No. 303A (Wren)

Wren is a mains powered, single tape processor controlled Answering and Recording machine giving many advanced facilities within a compact case design and may be desk or wall mounted.

Wren supersedes the existing Robin Answering and Recording Machine 202A.
Facilities of Wren are as follows:-

Outgoing Message - Up to 2 minutes. Press and hold Ans/Rec button to record outgoing message.

Outgoing Announcement Check - Press Ans/Rec button once.

Paytone detection - Up to 15 second delay of OGM if paytone is present.

Incoming Messages - Up to 3 minutes. Total message time is about 25 minutes using a standard.Microcassette MC-60 tape.

Memo message - No limit, up to end of tape. Press and hold the Memo button.

Message Play - Press Play once.

Message Save - After Wren has reset to answer, press Answer button until machine beeps once. Counter indicates number of calls saved.

Calling Party Control - (CPC switch ON, Line break stop)

VOX Stop - Low and High (LO HI) sensitivity, switchable.

Branchphone reset - Will release machine from the line should the handset of the associated telephone, or any parallel telephone, be lifted. If Wren does not detect the off-hook condition initially, replace the handset briefly. Wren will then disconnect the line.

Call Monitoring - Volume Control must be turned up to listen.

Built in microphone - To record outgoing and memo messages.

Pause - Maximum pause is 60 seconds. Press play once while listening to messages, press play again to continue.

Fast Forward and Rewind - Press and hold arrowed keys.

Integral phone socket - Does away with need for phonesocket doubler.

Volume Control - From zero to maximum volume.

Combined power on, counter and machine information LED indicator.

Uses standard Microcassette MC-60 tape.

Ring adjuster 2 or 4 rings. No manual ring facility.

Remote set to Answer - Call machine and let it ring 20 times to turn machine on remotely. Mains supply to machine must be turned on.

Remote Interrogation - Tone and Voice. Tone (MF4) use gives a two digit security code.

The two methods of interrogating the machine remotely are as follows:-
  1. By responding with speech or silence to tone signals given from the machine after listening to the Outgoing Message (OGM). The switch in the tape compartment MUST be set to "Voice" to use this facility.
  2. Or by responding with tone signals from an MF4 remote interrogator or telephone after listening to the announcement. Digit "1" stops the machine and it responds with a single beep. The two security digits must now be keyed, waiting for the beep response after each digit is keyed. The security code number and the switch are both found in the machines tape compartment. The switch MUST be set to Tone to use this facility.

The two digit security code is set at manufacture and will be changed at monthly intervals. Up to two attempts can be made to interrogate the machine remotely, if unsuccessful on the second attempt the machine releases the line. Other attempts can then be made.

Team Concepts International Ltd (Hong Kong)

BT supply on Sale terms only.

Approval Number S/1000/3/K/501618

Approved as supplied for connection to the Public Switched Telephone Network (PSTN), PBX 2-wire extensions.

The restriction of connection to 1+1 carrier (WB900) of any "plug-ended" equipment is currently under review and is expected to be lifted very shortly.

Not approved for Shared Service or to be used as an extension to a payphone. Not suitable for use on PBX's where manual ringing is applied. i.e. no manual ring facility or for use on "C" wire PMBXs.

A Phone Socket and a 240 volts, 13 amp, 50 Hertz mains supply are required within 3 metres of wren.

Wren is suitable for use on Phone Socket installations on DELs and most types of PBX extensions that provide automatic ringing. (No manual ring facility). Not suitable for use on "C" wire PMBXS.

Ringer Equivalence Number of Wren is 1.

Normal settings for DEL and PBX extension use. VOX SENS Hi, CPC ON.

The machine contains no on-site serviceable parts, therefore maintenance is limited to functional testing, checking the output of the plug-top transformer. the line and telephone cords are correctly positioned and the facility switches are set for optimum performance of the machine to match the line to which it is connected. The condition of the tape should be checked i.e. is it tightly wound on its spool, or is it badly creased or torn and the play head inspected for cleanliness. If suspect, the user should purchase replacement tape and clean the tape head as detailed in the "Troubleshooting Section" of the User Guide.

If the machine has failed completely, the output voltage of the Transformer should be checked. The output is marked 12v AC, but will measure about 16 volts when tested with the output open circuit.

New units carry a 22 month warranty from the date of manufacture, identified by the first 4 digits (YY WW ******) of the 10 or 11 digit serial number marked on the underside of the machine. (note: the 'week' digits are added to the label during production - they may appear as slightly different to the other digits).

Description                                                   BT Item Code
Answering and Recording Machine 303A (Wren, Charcoal Grey)    870398
Complete with Transformer & Cassette
Answering and Recording Machine 303A (Wren, White)            870458
Complete with Transformer & Cassette
BT Remote Interrogator                                        870427
(Suitable for use with all current BT Answer Machines)
User replaceable items:-
Message Tape MC 60 Microcassette                              870435
Button batteries for Interrogator 3 x V13GA or equivalent

Normal test conditions while idle. After answering the machine loops the line.

There are two problems that can occur with Robin, i.e. releasing calls after about 10 seconds when connected to long lines, and not resetting to the Answer mode after a power interruption. Both have been addressed and cleared in the design of the new Wren Answering and Recording machine.

Unlike many Answering and Recording machines, Wren detects ringing from LJU terminal 3 and 5 using the LJU capacitor. This method of connection overcomes the excessive capacitance problem often complained about by engineers on many earlier machines. It will loop the line after the number of ringing cadences set by the ring selector switch, 2 or 4. The ringing detection circuit is designed to recognise both PSTN and all internal ringing cadences generated by BT PBX's.

The circuit will ignore the initial long burst of ringing given on some TXK exchanges, and for this reason is not suitable for connection to PMBX's with manually applied ringing. i.e. THERE IS NO MANUAL RING FACILITY.

The unit is unable to recognise ringing signals outside British Standard specifications. In particular it will not recognise 50hz ringing signals sometimes used on fax 'smart' boxes and 'level 81 diallers'. A similar problem occurs with WB900 Mk8 pair gain systems.

VOICE/TONE DETECTION (Voice Operated Switch - VOX)
Wren is able to differentiate between voice and tone signals. It is required to hold the line to voice signals, but release the line when a network tone or silence is present after 6 seconds.

Differentiation is carried out by the VOX detecting the frequencies of the incoming signals. Network tones being of low frequency, whilst speech contains both low and mid-band frequencies. Therefore, if the machine sees low frequency signals, the signal is detected as a network tone and it releases the line. If mid-band frequencies are present, the signal is detected as speech and the machine stays connected and records the incoming speech.

The VOX sensitivity has been increased and a High and Low sensitivity switch provided. The normal switch position is High. In this position it is possible that line noise may be detected as speech. If this happens the machine will record line noise up to its maximum message length of 3 minutes. A Low setting is therefore provided for use in cases where line noise causes persistent problems.

The total time for reset depends on the number of messages recorded. It will be about 20 seconds for one message and 70 seconds if the tape is nearly full.

When the machine answers the line, it checks whether paytone is present. If paytone is detected, the OGM is delayed for up to 15 seconds. It is also possible that mains hum on the line can be mistaken for paytone, this to can delay the sending of the OGM. Setting the VOX switch to Low may overcome this problem.

Modern exchanges such as System X and Y, generate a 100 ms line break on the called parties line when the calling party clears down, this is a called a "Disconnect Clear Signal". (On Strowger exchanges it was often called the "K" break). Shorter line breaks are generated by most other exchange types. When the CPC switch is set to the ON position, Wren will detect a disconnect clear signal of about 2 and 5 ms depending on line length. This will cause the immediate release of the machine from the line without the need to wait for network tones. There is a risk that line breaks occurring on the network could cause false operation / release. As a precaution, an ON/OFF switch has been included to disable the CPC facility (leaving the Wren dependant on the VOX).

The Wren makes the decision to answer a call one ring before the set figure and also ignores line conditions for 1 second after answering. These factors create a short window during which the off-hook detection facility is inoperative, effectively just before and after answering a call.

This socket only extends the speech pair, earth and shunt wires from the LJU. Wires 1 & 6 are not extended which may prevent proper operation of some systemphones, e.g. 208H

The unit records back-up data on the section of tape immediately in front of the OGM. The information stored is as follows:-

- OGM length - number of messages stored -

Whenever the unit is powered up, it reads this data from the tape. It is possible when the tape is worn, or the heads are dirty, the data can be read in error. Should this happen the unit can think that the OGM is either shorter or longer than it actually is, with the consequence that either only part of the OGM will be played, or the OGM will be replayed together with some ICM recordings. This problem should not occur if the customer follows the recommendations in the user guide. i.e. change the tape at 6 monthly intervals and turning the tape over after 3 months.

On each occasion the tape is changed or turned over, the tape head should be cleaned and a new OGM MUST be recorded.

It has been found that Wren effectively re-transmits radio frequency signals received from cordless telephones together with a 50Hz component. This may cause interference on the cordless telephone. A modification will be available to resolve this problem in due course.

In the BT 1992 catalogue

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Last revised: November 26, 2010