Nortel DMS-100 Series General Description Manual page 26

1-10 DMS-100 ringing overview
Revertive calls (calls from a subscriber on a multiparty line to another
subscriber on the same party line) are permitted in the superimposed scheme.
The calling party receives revertive ringing while the called party is being rung
if the calling party is on the opposite side, tip or ring, of the called party, or the
calling party is on the same side but with the opposite polarity of the called
party.
If the calling party is on the same side with the same polarity as the called
party, the calling party, after going on-hook, is rung simultaneously with the
called party.
The following figure illustrates a call being placed from the tip side of a
multiparty, superimposed ringing line to a party on the ring side of the same
line with a negatively-biased ringer.
297-1001-131 Standard 06.01 October 2000