[Asterisk-Users] How to strip a digit

[Erick Perez]

I have the following extension to dial outside via SIP
it's like this:
phone----asterisk-----internet-----SIP provider----USA

exten => _91NXXNXXXXXX,1,AGI(call_log.agi,${EXTEN})
exten => _91NXXNXXXXXX,2,Dial(${SIPtrunk}/${EXTEN},55,o)
exten => _91NXXNXXXXXX,3,Hangup

I want to strip the digit 9 before sending it to the SIP provider.
Also, any suggestions for the above definition?
Thanks,

Erick.

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