Nortel DMS-100 Series General Description Manual page 27

Figure 1-8 Call on multiparty superimposed ringing line
1. Calling party (party 2) goes off-hook and dials called party (party 4).
Tip
Ring
2. The called party (party 4) receives negative-biased ringing signal.
Tip
Ring
3. When called party answers, revertive ring on calling party's side ceases,
indicating to the calling party that the called party has answered. Calling
party then goes off-hook and the call enters the talking state.
Tip
Ring
Note 1: +R indicates positive-biased ringers and -R indicates negative biased
ringers.
Note 2: This diagram does not show the ground connections of the tip and ring
circuits. These grounds are provided at the subscriber's location.
(see note 1)
Party 1
Party 3
Party 1
Party 3
Party 1
Party 3
DMS-100 Family DMS-100 Ringing System BASE15 and up
DMS-100 ringing overview 1-11
+R
Party 2
+R
Party 4
+R
Party 2
+R
Party 4
+R
Party 2
+R
Party 4
--R
--R
--R
--R
--R
--R