what's is reverse polarity charging function?
charging, reverse polarity charging，It means to notify the charging terminal (which can be a meter or an IP supermarket, etc.) of the charging start point and the charging end point through the polarity reversal on the A and B lines when starting the call and ending the call.
The polarity is reversed (ANC) after the receiver picks up the phone, and the polarity is reversed again after hanging up, so that it produce the charging signal;
The reverse polarity signal can only be sent by the user circuit of the switch where the calling user is located; You can use a multi meter to measure the polarity from positive to negative or vice versa.
When off-hook to start a call, the user port provides a voltage, If the meter is connected, the meter will start charging, When the call ends and hang up, the user port will provide a reversal voltage again and the meter will stop charging.
Reverse polarity, as the name implies, is that the polarity (the positive and negative poles of the A and B lines of the telephone line) is reversed. As for when to reverse: 1: The called party picks up the phone and talks 2: The call ends and hangs up. The polarity reversal will generate a pulse, so that the meter can record the start time and end time of the user’s call to complete the pricing. This feature is mostly used in Public telephones.
Our TAKFIBER's PCM telephone multiplexer can support this function, Following is one picture of our PCM telephone multiplexer for reference:
The polarity is reversed (ANC) after the receiver picks up the phone, and the polarity is reversed again after hanging up, so that it produce the charging signal;
The reverse polarity signal can only be sent by the user circuit of the switch where the calling user is located; You can use a multi meter to measure the polarity from positive to negative or vice versa.
When off-hook to start a call, the user port provides a voltage, If the meter is connected, the meter will start charging, When the call ends and hang up, the user port will provide a reversal voltage again and the meter will stop charging.
Reverse polarity, as the name implies, is that the polarity (the positive and negative poles of the A and B lines of the telephone line) is reversed. As for when to reverse: 1: The called party picks up the phone and talks 2: The call ends and hangs up. The polarity reversal will generate a pulse, so that the meter can record the start time and end time of the user’s call to complete the pricing. This feature is mostly used in Public telephones.
Our TAKFIBER's PCM telephone multiplexer can support this function, Following is one picture of our PCM telephone multiplexer for reference:
Address: NO.220, Qiutao Road, HangzhouCity,Zhejiang Province, China 
Tel: 0086-571-28184719
Fax: 0086-571-28184719
