An ITSP (Internet Telephony Service Provider) offers an Internet data service for making telephone calls using VoIP (Voice over IP) technology. Most ITSPs use SIP, H.323, or IAX (although H.323 use is declining)[citation needed] for transmitting telephone calls as IP data packets. Customers may use traditional telephones with an analog telephony adapter (ATA) providing RJ11 to Ethernet connection .Which types of high-density trunk can be used to connect to an ITSP? (Choose all the apply.)
A.
T1/E1 CAS
B.
FXS
C.
T1/E1 PRI
D.
E&M
ABCD