i am working in ISP and i have a CCNA. if u want to work there you need to be qualified in :
A. Boder Gateway Protocol.
C. VPRN Networks.
D. RIP V 1&2
F. IGRP , EIGRP
H. WAN Tech. Like : ATM , FR , Super FR , SifraNet , VC , MicroLan and Point To connections.
I. Don't forget the security side and u need to know : Checkpoint firewalls , Cisco PIX & ASA and ForiGate Firewall ( like FortiNet 60 , 100 and 500 ).