Service Observing Unit

CM 10 & CM 30
CM-10 and CM-30


Dees Service Observing units provide complete call monitoring and talk assist capabilities. They are compatible with almost any analog telephone system, e.g., POTS, CENTREX, PBX or Key System lines. Available in two versions, Model CM-10 monitors up to 10 lines and CM-30 monitors up to 30 lines (up to 90 lines using Expander).

To monitor lines, assign a supervisor’s telephone set and numbers for those lines you wish to monitor. Then, using the Supervisor’s set, dial the numbers for the line you want to monitor. You may move from one set to another by briefly hanging up and then dialing the new number, or by dialing the pound button (#) and then the new number. When the line is being monitored, nothing can be heard by the parties on the lines. However, if preferred, an optional Alert Tone can be turned on to indicate to the conversing parties that the line is being monitored.

The CM-10 and CM-30 have a built in Talk Assist feature to allow the supervisor to enter into a call whenever necessary. It is easy to activate with a strapping option. The observer simply presses the asterisk button (*) on his or her phone set. No add-on products are required for this feature.

As your business grows, the CM-30 can grow with you. The CMX-300 Service Observing Expander will expand your system to monitor up to 90 lines in increments of 30 lines per unit. (Note: CM-10 does not support Expander)


If you are in the kind of business where your survival and success is dependent on your sales and service representatives making effective use of the telephone to reach the marketplace, the Dees Service Observing units will be invaluable to you. They’re ideally suited to telemarketing firms, sales order desks, technical support desks, customer service departments, service departments, etc. With the CM-10 or CM-30 installed, you can monitor any or all calls made by your sales and support staff from your telephone set whenever you want. These units are also ideal for training purposes. During a training session, if a trainee gets into difficulty during a call, you can activate the Talk Assist feature and join in on the call to help. If you prefer to let the callers know that they are being monitored, activate the Alert Tone option. Add the Model 340 DeesLink to allow secure monitoring from a remote location.


Installing the Dees Service Observing units is straight-forward and consists mainly of tying down the cross connects of the CM-30 or CM-10 to those lines you wish to observe. Each unit requires 24 VDC, and comes with a plug-in power supply.

CM Install Diagram


  • Available in 10 and 30 line capacity units
  • 30 line version (CM-30) is expandable up to 90 lines using the CMX-300
  • Compatible with analog POTS, Centrex, PBX or Key System lines
  • Built-in Talk Assist option included
  • Silent observing with optional Tone Alert provided
  • Remote monitoring using DeesLink
  • Connectorized interface
  • Can be wall mounted
  • Operates from a 24 VDC unregulated power supply


Ordering Information

CM-10/PSUService Observing Unit – 10 Lines
with Power Supply (Model 368CM)
CM-30/PSUService Observing Unit – 30 Lines
with Power Supply (Model 368CM)
CMX-300Service Observing Expander – 30 lines
CM-10RService Observing Unit – 10 station rack mount


Operating Supply Voltage24 30VDC
Operating Supply Current  150mA
Tone Dialing Parameters    
Loop Length 580 ohms
Interdigital Time40  msec
Input Signal Level-7.5 4dB
Bandwidth 2 %
Recognition Time40  msec
Alert Tone    
Frequency 1 KHz
Duration 0.4 sec
Relay Contact Ratings    
Lamp at 10 VAC 2 amps
ECI and EC2 at 28 VDC 2 amps
TAI and TA2 at 28 VDC 2 amps
Breakdown Volts    
Observed lines to ground  1000VDC
Operating Temperature32 122°F
 0 50°C
Humidity (non-condensing)  95 %RH

Dimensions (LxWxH)
Unit: 9.3” x 5.4” x 1.6” (23.5 x 13.7 x 4 cm)
Packaged: 10.8″ x 6.4″ x 4.4″ (27.3 x 16.2 x 11 cm)

Shipping Weight

CM-10/PSU2.1 lbs. (0.95 kg)
CM-30/PSU2.3 lbs. (1.05 kg)


CM-10/PSUOne A25B (RJ21) or equivalent 25-pair
cable with female connectors
CM-30/PSUTwo A25B (RJ21) or equivalent 25-pair
cable with female connectors


Apparatus cabinet, relay rack or backboard


Approval Number

DOC CS03350 3518 A
DOC C108-8 Class AApproved
CSA C22.2 No. 225-M90LR 91817
FCC Part 68FCNCAN-61252-PX-N
FCC Part 15 Class AApproved
UL 1459-2D0292442DBC

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