Electronic and Postal Communications (Quality of Service)
G.N. No. 416 (contd)
_______
THIRD SCHEDULE
_______
(Made under Regulation 10)
QUALITY OF SERVICE PARAMETERS FOR INTERNATIONAL
TELEPHONE SERVICES
S/NO
Definition
1
The relationship between
the number of seizures
that result in an answer
signal and the total
number of seizures.
Measurement
Target Values
Answer Seizure Ratio (ASR)
Percentage of seizures
For active test calls placed by
resulting in answer signal
some test systems [ITU-T
Rec. E.426]:
(ITU-T Rec. E.425)
Effective call attempts should
ASR: ≥ 80%.
be more than 60%.
NER: ≥ 90%.
2
The relationship between
the number of seizures
and the sum of the
number of seizures
resulting in either an
answer message, or a
user busy, or a ring no
answer, or in the case of
ISDN a terminal
rejection/unavailability
3
The call set up time can
be defined as the time
interval from the instant
the user initiates a
connection request until
the complete message
indicating
call
disposition is received by
the calling terminal.
4
Network Efficiency Ratio (NER)
Percentage of seizures
For active test calls placed by
resulting in answer signal or
some test systems: NER: ≥
user failure(ITU-T Rec.
90%.
E.425)
Effective call attempts should
be more than 60%.
Call set-up time
Mean values (in seconds)
(ITU-T Rec. E.721; ITU-T
Rec. E.771)
Mean value of International
call set-up time: < 8sec
Blocked Call Rate
Percentage of
unsuccessful calls. An
unsuccessful call is call
attempt to a valid
number, while in a
coverage area, where
Probability of end-to-end
blocking (ITU-T Rec. E.771)
17
Mean value of end-to-end call
blocking: < 5%