In H.460 networking, what is the code stream hole between the public network and private network terminals maintained?

exams H11-861_V2.0-ENU V1 H11-861_V2.0-ENU exam 0 Comments

In H.460 networking, what is the code stream hole between the public network and private network terminals maintained?
A . Timed keep alive package
B. Tunnel
C. IRQ heartbeat message
D. No need to maintain, the stream channel is established after the hole is opened

Answer: A