Multiple incoming numbers - CallerID?

I have an ISDN2 line with 4 external number. How do I link these incoming numbers to the specific sip phone ? for example :

050-3251001 -> sip/phone1
050-3251002 -> sip/phone2

is this done in zapata.conf or in extensions.conf and how ?

Could someone please explaine. I cant find this in any documentation.

Something like this:

exten => 1001,1,Dial(SIP/phone1,20)
exten => 1001,2,Voicemail(u1000)
exten => 1001,3,Hangup

exten => 1002,1,Dial(SIP/phone1,20)
exten => 1002,2,Voicemail(u1000)
exten => 1002,3,Hangup

I tried that but I got errors like :
Extension ‘s’ in context ‘incoming’ from ‘xxxxxx’ does not exist. Rejecting call on channel 0/2, span 1

Somehoe it just needs a ‘s’