Page 111 - Intelligent Communication Systems

" CHAPTER 9 / DESIGN METHODOLOGY FOR TELECOMMUNICATION SERVICES 93

pots-1) idle (A) offhook(A): dialtone(A).

pots-2) dialtone (A), idle(B) dial (A, B): ringback(A, B), ringing(B, A).
pots-3) ringback(A, B), ringing(B, A) offhook(B): path(A, B), path(B, A).
pots-4) path(A, B), path(B, A) onhook(A): idle(A), busy(B).

pots-5) dialtone(A), not [idle(B)] dial (A, B): busy-dial (A, B).
pots-6) dialtone(A), onhook(A): idle(A).
pots-7) ringback(A, B), ringing(B, A) onhook(A): idle(A), idle(B).
pots-8) busy (A) onhook(A): idle (A).
pots-9) busy-dial(A, B) onhook(A): idle(A).

pots-10) dialtone(A) timer (dialtone (A)): howler(A).
pots-11) busy-dial (A, B) timer (busy-dail (A, B)): howler (A).
pots-12) busy (A) timer (busy (A)): howler(A).

pots-13) howler (A) onhok(A): idle (A).
pots-14) timer : dialtone (A) 5sec.
pots-15) timer : busy-dial (A, B) 5sec.
pots-16) timer : busy (A) 5sec.

FIGURE 9.1 I POTS description.

path(A, B) means the establishment of a path between A and B. Then a
caller and the called party can communicate by talking or exchanging
information.
path(B, A) means the establishment of a path between B and A.
idle(A) means that terminal A is idle.
busy(B) means that terminal B is busy,
not [idle(B)] means that terminal B is not idle.
busy-dial(A, B) means that terminal A hears a busy tone from terminal B.
timer [dialtone(A)] is an event, and it means that a dialtone is heard at
terminal A and a timer works at terminal A.
howler(A) means that a howler tone is heard at terminal A.
timer is defined in the lines for pots-14, -15, -16 in Figure 9.11. For example,
at line pots-14, a timer works in 5 seconds in the dialtone(A) state.