Nortel RLC Installation And Administration Manual page 44

RLC description
Nortel CTI and ACD applications
The RLC operates with all Nortel computer telephony interface (CTI) and
automatic call distribution (ACD) applications.
Classes of service RNGI and RNGB
Remote Gateway 9100 Series supports classes of service RNGI and RNGB.
Class of Service RNGI: Class of Service RNGI permits digital telephones
to ring rather than buzz when they are offhook.
Class of Service RNGB: Class of Service RNGB, like RNGI, applies
ringing to digital telephones that are idle but offhook, but unlike RNGI it
also applies ringing to digital telephones that are busy and offhook on
another line.
Local TCM ports on the RLC support these features. However, digital telephone
sets connected to Remote Gateway 9100 Series units do not support RNGI,
RNGB, DRG2, DRG3 or DRG4. Digital telephone sets connected to Remote
Gateway 9100 Series units support DRG1, the default ring.
Note: The RNGI and RNGB features are only available if there are no local calls
present on the digital telephone set. If a local call is present on the digital
telephone set, the ringer is converted to a beep tone (tone B message).
18 RLC Installation and Administration Guide
Standard 4.0