Trouble getting ultra-simple dialplans to work

Newbie user, going through chapter 4 of the O’Reilly Asterisk TFOT book

Platform is Asterisk 1.2.0 on a 2.5-GHz Pentium with 1 GB RAM, and a TDM400P card with 1 FXS module and three FXO modules.

The FXS module is connected to a plain old analog phone, and the FXO module is connected to the wall.

Here is my dialplan:

exten => s,1,Answer
exten => s,2,Dial(Zap/1,15)
exten => s,3,Wait,1
exten => s,4,Playback(vm-nobodyavail)
exten => s,5,Wait,1
exten => s,6,Playback(vm-goodbye)
exten => s,7,Wait,1
exten => s,8,Hangup
exten => s,103,Wait,1
exten => s,104,Playback(tt-allbusy)
exten => s,105,Wait,1
exten => s,106,Playback(vm-goodbye)
exten => s,107,Wait,1
exten => s,108,Hangup

As best I can tell from the Asterisk book, what is supposed to happen is that the incoming call is immediately routed to whatever is connected to the TDM400 port 1. If it times out with no answer, it says “Sorry, nobody available” and hangs up. If the phone connected to TDM400 port 1 is off-hook, the caller should hear “All lines are busy” and the system should hang up.

What is happening is that the caller gets “Sorry, nobody available” in EITHER case (timeout with no answer, or local phone is off-hook). If the phone is off-hook, the caller gets that message after one or two rings. If the phone is on-hook and doesn’t answer, the caller gets four or five rings until timeout then gets the message. So, it appears that detection of “busy” might be happening, but redirection to priority n+101 (in this case, priority 103) isn’t happening.

I’ve looked everywhere I can think of and can’t find an answer. Any suggestions?

What is happening is that the caller gets "Sorry, nobody available"
in EITHER case (timeout with no answer, or local phone is off-hook).
If the phone is off-hook, the caller gets that message after one or
two rings.

Actually, I said that wrong. If the phone connected to port 1 is off-hook, the caller gets the “Sorry, nobody available” message immediately, with no rings first. If the call times out with no answer, the “Sorry, nobody available” message comes after four or five rings. The point is, though, that the “All lines are busy” message never shows up.

Disregard the question … I found the “priorityjumping” parameter in the extensions.conf file was set to “no”. Hmmm … seems that the “priorityjumping” parameter isn’t mentioned in the Asterisk_TFOT book either.

not surprising… asterisk development moves fast and the priorityjumping option is relatively new…