Private Integrated Services Network (PISN)
- Inter-Exchange Signalling Protocol - Call Priority Interruption
and Call Priority Interruption Protection Supplementary Services
3rd edition (December 2001)
This Ecma Standard specifies the signalling protocol for the
support of the Call priority interruption (SS-CPI) and Call Priority
Interruption Protection (SS-CPIP) supplementary services at the
Q reference point between Private Integrated services Network
eXchanges (PINXs) connected together within a Private Integrated
Services Network (PISN).
This edition of this Standard does not apply to calls using the
circuit-mode multiple rate bearer service.
SS-CPI allows a call request for a priority call to proceed successfully
in the case that there is no user information channel available.
This is accomplished by force releasing an established call of
SS-CPIP allows for the protection of calls against interruption
from priority calls.
The Q reference point is defined in ECMA-133.
Service specifications are produced in three stages and according
to the method specified in ETS 300 387. This Ecma Standard contains
the stage 3 specification for the Q reference point and satisfies
the requirements identified by the stage 1 and stage 2 specifications
The signalling protocol for SS-CPI(P) operates on top of the
signalling protocol for basic circuit switched call control, as
specified in ECMA-143, and uses certain
aspects of the generic procedures for the control of supplementary
services specified in ECMA-165.
This Standard also specifies additional signalling protocol requirements
for the support of interactions at the Q reference point between
SS-CPI(P) and other supplementary services and ANFs.
Additional interactions that have no impact on the signalling
protocol at the Q reference point can be found in the relevant
stage 1 specifications.
This Ecma Standard is applicable to PINXs that can interconnect
to form a PISN.
The protocol defined in this Standard forms part of the PSS1
protocol (informally known as QSIG).
The following file can be freely downloaded:
||Acrobat (r) PDF file
This Ecma publication is also approved as ISO/IEC 15992.
The previous replaced "historical" editions of this Ecma Standard are available here.