Cisco Unified MeetingPlace

Field Notice: FA00152 - Cadence Beeping (Short Galloping Noise)

May 26, 2004

Products Affected



MeetingPlace Server


Problem Description

Note: This Field Notice is a legacy Latitude Field Notice that has been converted to the Cisco format so the information would remain available to their customers.

In certain MeetingPlace conference calls, a low level noise sounding like cadenced beeping was heard. The noise occurred seemingly randomly and infrequently

End users who attended a MeetingPlace meeting with their PBX desk phone sometimes picked up interference from nearby cell phones transmissions. Some cell phones due to the nature of their transmission formats introduced cadenced beeping noises.

MeetingPlace end users who placed their cell phones very close to the desk phone were most at risk of introducing cadenced beeping or other noises into the meeting. The desk phone and particularly the headset amplifiers, headsets, and connecting wires could be very susceptible to external electrical noises. The randomness and frequency of the issue was due to non-deterministic nature of end users placing and receiving calls from their nearby cell phone.

Analysis of the cadenced beeping waveform extracted from meeting recordings and voice captures showed signal framing structures consistent with the GSM standard of wireless systems. Cingular Wireless is the only North American GSM wireless provider, but the system is very common in Europe and Asia. Other wireless systems may introduce other noise patterns due to their differing transmission waveform structures.

Problem Symptoms

The impact on MeetingPlace participants ranged from no impact, ignore the noise and proceed with the meeting without a hitch, to annoyance and interruption of the meeting flow for someone to exclaim, "What was that?!" As the end user base became more aware of the problem, fewer people ignored the noise so meeting flows were further affected.

Cadenced beeping was originally perceived as a MeetingPlace issue, particularly M3 R5, because it was heard more frequently after the switchover from PCI to M3 R5. However, since the noise could be introduced at any desk phone, the cadence beeping might be heard on any MP meeting in addition to person-to-person telephone calls. There was one reported instance of cadence beeping on a person to person call.


Keep cell phones at least two feet or more away from corded or PBX desk phones, headsets, handsets and associated connecting wires. In general, any source of radiated electrical noise signals such as:

  • Computer or television monitors

  • Wireless devices -cell phones, cordless phones, pagers, wireless PDAs, wireless LAN switches/hubs

  • High power or high voltage equipment - transformers, ovens, fans

should be located as far away from telephones used for attending meetings as possible to minimize interference.

For More Information

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