Huawei EM770W User Manual page 13

Note:
„
DSR (Data Set Ready) signal is not supported in this RS232 serial port.
„
The COM1 supports data services. When EST1 signal in EM770W module is pulled down to
GND, COM1 is used for debugging only.
COM2 for RS232 serial port
This RS232 serial port is 5-wired, which is as follows:
This port can also be connected to the RS232 port of PC directly.
Phone interface
A single-port internet interface connector is provided on the DEMO board, which can be
connected to the phone handle.
When EST1 signal in EM770W module is pulled down to GND, COM2 can not be used.
Earphone interface
A 2.5mm earphone jack is provided on the DEMO board, which is as follows:
The signal distribution of this interface is as follows:
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