PHP400 GSM Help Point.
5
3.
Operation / Testing
3.1.
Making a Call
To make a call, press the required button and wait for connection. The unit will seize
the line and then automatically dial the pre-programmed number.
3.2.
Answering calls
To receive a call, press any button when ringing is heard.
3.3.
Ending the Call
There is no direct way for a user to end a call from the unit. The unit will close down
when the remote party clears. Depending on how the network handles this, a tone may
be heard from the Help Point for a short period of time (up to 5 seconds) before it closes
down.
3.4.
Testing the GSM module
To check that the GSM module is operating correctly, send an SMS message to it (ie to
the telephone number of its SIM) as follows:
1234st
It will respond with an SMS containing the following diagnostic information:
•
Signal level (must be between -90dBm and -50dBm)
•
Charger status (should say “on”)
•
Battery voltage (an internal voltage, should be between 4.1 and 4.2)
•
Temperature (now, min & max) Note that min and max will show 127 or 128 on
first reading after power up.
•
IMEI (the IMEI number of the GSM module)
•
Firmware version
This information will verify that the unit is on the network and can help diagnose various
problems.
In particular if the Signal level is between -110dBm and -91dBm then it is too low – Help
Point operation will not be reliable until the signal level is increased, for example by
repositioning the antenna or choosing a different network.
3.5.
Call timer
The phone has a programmable call timer that can limit the maximum call duration.
When ON, the timer forces the phone back off line after the preset time. This prevents
the line remaining tied if the neither party ends the call. The timer is factory-set to 7mins
by default, but can be set to any value (up to 2¾hrs) or disabled. See section 6.3.1.
3.6.
Semi Duplex Operation
The Help Point is semi duplex, with automated switching between transmit and receive
depending on which signal is the stronger. It therefore requires an adequate signal
level to be able to switch into receive mode. This level may vary according to ambient
noise levels at the Help Point, but we would recommend ensuring that the incoming
signal level received at the analogue telephone port is at least -35dBm.
Summary of Contents for PHP400
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