Call Routing with Asterisk

Hi folks,

I am new to asterisk.
I would like to know how to do this:
When a registered user dial a specific prefix, for example 1234, the call to be routed to an application server in a different IP address.
I will appreciate any responses.
Thanks,

  Jefferson

Could use more info. What is the application server speaking sip,iax,PRI,other ?

I route calls to a LD provider throught the net. I use IAX. you have to configure the iax.conf file for the connection to the provider then you do the call routing in the extensions.conf example

exten => _1NXXNXXXXXX,2,Dial(IAX2/LDprovider/${EXTEN})

this says any number starting with 1 and is 10 didgits long send to LDprovider by number dialed