[asterisk-users] Alphabet character in destination number (CDR)

J Montoya or A J Stiles asterisk_list at earthshod.co.uk
Fri Mar 31 07:07:50 CDT 2017

On Thursday 30 Mar 2017, Ikka Tirtawidjaja wrote:
> Dear all,
> I have PBX with asterisk 13.x
> a couple of IPPhone that connect to that asterisk PBX send an alphanumeric
> dialed phone number.
> for example, in my CDR table, field DST, it show dialed phone number like
> - 0C81318304632C  (it should be 081318304632)
> - 08D11157112 (it should be 0811157112).
> Why it's happening ? and how can I prevent it to happen ?

A, B, C and D are actually valid DTMF digits  (they belong in a column to the 
right of 3, 6, 9 and # respectively, and have the "high" frequency 1633 Hz).  
TTBOMK they were never actually used for anything in practice, they just keep 
kicking around like a vestigial organ  (compare how computer software for the 
UK financial industry still includes code to deal with mediaeval pounds, 
shillings and pence).  

Is it possible for a 1633 Hz tone, loud enough to swamp the "high" frequency 
of a dialled digit, to be finding its way somehow into the microphone of the 
affected phone and confusing it when digits are dialled?


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