Charge Advice Information (CAI)

Charge Adviice IInnffoorrmaattiioonn ((CCAAII))

• CAI supplied to MS by the network
• Enables MS to calculate Advice of Charge (AOC) data
• Comprises all or a combination of the following
parameters:
• e1 – Units per interval
• e2 – Seconds per time interval
• e3 – Scaling factor
• e4 – Unit increment
• e5 – Units per data interval
• e6 – Segments per data interval
• e7 – Initial seconds per interval

On every successful request for an applicable telecommunications service, the network
supplies the MS with Charge Advice Information (CAI) in the form of signalling information.
This information enables the MS to calculate the units associated with the requested service in
real time in the form of an Advice of Charge (AOC) value. Any change in the charging rate
during a call may be indicated to the mobile station.
The CAI provides charging information, indicates the charging point and initiates the timing
of the chargeable duration. The CAI information sent to the MS from the MSC consists of
seven elements, however it need only contain those elements required for the particular
situation. If elements are missing from the initial CAI message of a call, they shall be treated
as zero. The seven elements are as follows:
Element e1 -
This element defines the number of units incremented per interval. It is set in terms of
LPLMN units/interval to a resolution as defined in the table above under RES.

Element e2 -
This element defines the time interval for unitization, and is specified in seconds, to a
resolution as defined in the table above under RES.
Element e3 -
This element defines the scaling factor to convert from LPLMN units to HPLMN units. It is a
dimensionless multiplier given to a resolution as defined in the table above under RES.
Element e4 -
This element defines the number of units to be incremented on receipt of the message
containing the CAI elements. It is specified in units of the LPLMN to a resolution as defined
in the table above
under RES.
Element e5 -
This element defines the number of units incremented per data interval. It is set in terms of
LPLMN units/interval, to a resolution as defined in the table above under RES.
Element e6 -
This element defines the data usage interval for unitization, and is specified in segments
(SEG), to a resolution as defined in the table above under RES., for Dedicated Access to the
PSPDN (whether directly or via Dedicated PAD). It does not apply to circuit switched access
to modems or PADs, (except Dedicated PAD's) or MS to MS calls.
Element e7 -
This element defines the initial time interval for unitization, and is specified in seconds, to a

resolution as defined in the table above under RES.