Free Cisco 350-801 Actual Exam Questions - Question 15 Discussion
Refer to the exhibit. An engineer configures ISDN on a voice gateway. The provider confirms that the
PRI is configured with 10 channels the engineer ordered and is working from the provider side, but
the engineer cannot get a B-channel to carry voice. The rest of the configuration for the serial
interface and voice network is functioning correctly. Which actions must be taken to carry voice?
C. The pri-group timeslots probably should be 0-9 for the 10 channels since router interfaces typically start counting from zero. If the engineer used 1-10, that might be why no B-channel is active. It’s a common gotcha with PRI configs on Cisco gear. The other options don’t really fit because the controller card is usually active by default, it’s a T1 interface so E1 isn’t relevant here, and manually reversing channels isn’t standard practice. Adjusting the timeslot range to 0-9 should fix it.
The INVITE definitely kicks off the call, then 200 OK confirms User 2 answered, followed by ACK to finalize the setup. BYE should be last for User 2 disconnecting. This matches standard SIP flow.
I think putting INVITE first makes sense since User 1 initiates the call. Then 200 OK after User 2 answers, and BYE last when User 2 hangs up fits the sequence best.
Looks like option C is a common trap here since it mixes up the signaling steps. Starting with the INVITE and ending with BYE seems more logical for this call flow.