Clear-Com uses the ETSI DECT Sync signal. Below this text is an excerpt from the spec.

Explanation of DECT sync can be found here Matrix: E-Que dect sync connections on multiple frames

The DECT sync signal appears across pins 3 and 6 of the E1 / Antennas RJ5 connector on the rear of the E-Que card

The FSII (E1) Antenna uses all 8 wires of the CAT5 cable on an E1 pin out when wired back to a splitter, base station or directly to an E-Que card.

It’s a 100 HZ pulse train with the positive pulses about 880 µs wide, and every 16^th pulse is 2640 µs , three times as wide.  

This same signal also appears on the dedicated DECT IN / OUT RJ45 connectors on the EQUE card / FSII Base  . The dedicated DECT Sync In / OUT connectors allows the user to pass Dect sync to other stand-alone DECT matrix / basestation or 3rd party devises who maybe sharing the same RF space

The pin out for the dedicated DECT Sync IN / OUT RJ45 is

B.2.1 Synchronization signal

• The synchronization signal  is a 100 Hz signal having positive pulses of width between 5 μs and1 ms, except for frame 0 (every 16th pulse), which has a pulse width between 2 ms and 5 ms. This signal establishes the10 ms DECT frame interval and the 160 ms DECT multiframe interval.
  
  

• The synchronization signal shall have a long term frequency accuracy of better than ± 5 ppm (nominal conditions) or± 10 ppm (extreme conditions).
  
  

• As the wave form is asymmetric, devices can establish proper timing relations in the event that the differential pair of input signal wires is (improperly) connected (pair inversion).
  
  

• The random phase jitter on the falling edge of the synchronization signal shall not exceed 0,5 μs rms. The differential amplitude shall be greater than 400 mV peak to peak.