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Friday, June 18, 2010

TON and NPI to PSTN

My client is using asterisk 1.4.22 with a 1-port digium card connecting to PSTN.  His PSTN provider recently upgraded the NGN and then all outgoing calls are sent with incorrect callerid.
 
It turns out that the NGN requires TON and NPI different from the default asterisk installation.
 
What the NGN needs are:
A-number (caller)
TON : unknown
NPI : unknown
 
B-number (callee)
TON : unknown
NPI : ISDN Telephony
 
There are two values in /etc/asterisk/zapata.conf related to TON and NPI.  They are:
 
pridialplan
prilocaldialplan
 
pridialplan affects the callee's numbering plan while prilocaldialplan affects the caller.
 
The default asterisk installation sets them to local/national.  In our client's environment, we have to make them as:
pridialplan=unknown
prilocaldialplan=unknown
 
More information regarding possible values can be found in http://markmail.org/message/rpd2aewiu2soostz
 
Note that we have to restart asterisk in order to make such changes effective.  Just reloading chan_zap.so is not enough.
 
With the 'unknown' setting, the NGN now presents a correct callerid to the receiver.
 
 
 

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