3.6.1.2 How to make Calls
A. Before Making Initial Call
It is similar to other calls in a telephone system to make a call in the DECT system except that every call to or from a wireless terminal involves establishing a RF link to the wireless terminal through a base station. In an idle status, a wireless terminal scans a dummy bearer from base stations and locks to the base station with the strongest signal. The dummy bearer is similar to the control channel in a cellular telephone system. If the wireless terminal can not synchronize to a dummy bearer, it can not make a call.
System ID(PARK) is very important in the DECT calls. The Base stations should be assigned to a unique
Calls to Wireless Terminal
The DECT system receives a call from an extension of the system.
To locate the called party, the DECT system sends a request containing the ID of the called wireless terminal to all base stations.
The called wireless terminal responds to the base station onto which it is locked.
The RF link is established. The call then proceeds like other calls in the office telephone system.
Initiated Call from a Wireless Terminal
The wireless terminal locks onto a base station and initiates a RF link.
The base station transmits call information to the DECT system. The call then proceeds like other calls in the office telephone system.
B. Controlling a Call
During a call, interaction occurs mainly between the wireless terminal and a DECT. The wireless terminal accepts input at the keypad by user and sends the information to a DECT via base station. The DECT handles most of signaling functions and controls the display of wireless terminal.
C. Terminating a Call
Call termination involves releasing a voice channel and transiting a wireless terminal to a standby status. When DECT recognizes that a call has terminated, it sends a release message to a base station. The base station and wireless terminal are released.
In some cases, the base station should initiate call termination by sending a message to the DECT. Loss of wireless terminal power and interference with the RF signal are examples of events that cause the base station to terminate a call abruptly.
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