DECT Telephone Systems deliver high-quality wireless voice communications to employees who roam within a building or campus. Popularized in Europe, DECT systems enable low cost, high quality, cordless telephony (using a single base station to connect one or more handsets to the public telecoms network). Enterprises have also deployed DECT systems including a cordless PABX, where calls can either be within the system or to the public telecoms network. Every major PABX vendor offers DECT access options. DECT can also be found in baby monitors, electronic cash terminals, traffic lights, and remote door openers.
The ISDN telephony network provides an 8 kHz clock signal to all connected equipment. This clock is ultra-stable, precise and derived from an atomic master clock in the Network. DECT base stations derive the DECT base frequency from this Clock. So what happens when an enterprise moves to VoIP? The Gateway installed now provides clock to the PBX - and thus, the DECT base frequency is derived from the Gateway.
Is this an issue? Yes it is. Most VoIP equipment manufacturers have not produced products which can interoperate with DECT because they have not considered the need for a High Precision Clock. The result is that the DECT frequency is not precise enough to generate a DECT base frequency and therefore the handset will not registered to the Base Station.