asterisk users - Sep 2014 - Identifying frequency tone in Asterisk

Hi,

I have 2 Asterisk systems and a unique scenario where I need to play a
particular tone on Asterisk1 and identify the same tone on Asterisk2.
Following is my call flow,
Asterisk1(Plays audiofile1,Wait for 2 Sec,Plays a tone,Plays audiofile2) ->
PSTN -> 3rd Party CONFERENCE SYSTEM <- PSTN <- Asterisk2(Record
audiofile1,Wait for a tone,Record audiofile2).
A few points to keep in mind,
(1)I can not send DTMF tones as Conference system suppresses it.
(2)There is no other way to pass information from Asterisk1 to Asterisk2
(3)Asterisk2 doesn't know the length of audiofile1,audiofile2. (files are
less than 200 Sec in duration)

I am thinking of changing a frequency of one of the DTMFs on Asterisk
2(dsp.c,let us say DTMF D, from 941,1633 to 951,1643) and playing that
frequency tone from Asterisk 1.
So On Asterisk1,
[play]
... ...
same => n,Playback(audiofile1)
same => n,Wait(2)
same => n,Playtones(951,1643)
same => n,StopPlaytones()
same => n,Playback(audiofile2)

And something similar to below on Asterisk2
[record]
... ...
same => n,MixMonitor(audiofile1)
same => n,Read(DATA,silence/1,1,,,200)
same => n,ExecIf($["${DATA}" = "D"]?NoOP(D
received):HangUp())
same => n,MixMonitor(audiofile2)
... ...
Do you see any harm in this solution? Can you suggest me a better solution?
I'll appreciate your responses.

Thanks,
--Satish Barot
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