Adding or subtitution of extensions numbers

Hi,
I would like to ask some question regarding on the extensions. In asterisk it is possible to strip a dialed number, right? Ande the extensions would look something like this.

[test]
exten=>_001,1,Dial(SIP/${EXTEN:2}|60|ro)
exten=>_001,n,Hangup

My question is like this. Is asterisk capable of adding or subtituting numbers on the dial plan? Take the example above, If the someone dial 001xx.xxx…, the asterisk will strip the 2 digits before digit number 1. Can asterisk strips that two digit and change it to other number?Or can asterisk add number/s when someone dial 001?

Please give some help on this one. Thanks

Regards,
newbie_aste