How in Asterisk in one numbering of Ats and sip numbers?

Question

Asterisk

Good day, task:
1) There is a sip Voip FXS gateway for 48 ports Numbering 1001-1048
2) There are clients connected via sip 1000, 1049-1XXX
How to write a dialplan for this condition so as not to go beyond the numbering 1XXX ??
Now
;GXW
exten => _1XXX,1,Dial(sip/192.168.1.7/${EXTEN})
exten => _1XXX,2,Hangup
;Sip Secr
exten => 1000,1,Dial(SIP/1000)
exten => 1000,n,Hangup
But now there will be a lot of sip clients, and it's not very convenient to enter them by hand.

Answer 1

exten => 1000,1,Dial(SIP/1000)
exten => 1049,1,Dial(SIP/1049)
exten => _10[0-4]X,1,Dial(sip/192.168.1.7/${EXTEN })
exten => _1XXX,,1,Dial(SIP/${EXTEN})