insys icom GPRS 5.1, Руководство пользователя, Страница: 85 / 102

INSYS GPRS 5.1 serial GSM, GPRS, and EDGE General
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8.8.3 Calculation example
We assume a GPRS rate for data with a 1kilobyte billing matrix, as offered by T-
Mobile and Vodafone as M2M rate.
Usually, GPRS network providers bill once daily, e.g. once a day the sum of all ac-
cumulated data since the last billing is rounded to the next billing unit (here: 1
kilobyte).
Example T-Mobile: Contract M2M Connect (Date: September 2005)

Basic fee: 3.95 Euro / month

Data extension M2M Data 1 for 1 Mb free volume: 2.95 Euro / month

Data extension M2M Data 2 for 2 Mb free volume: 3.95 Euro / month

Data extension M2M Data 5 for 5 Mb free volume: 4.95 Euro / month

Data extension M2M Data 10 for 10 Mb free volume: 6.95 Euro / month
The following examples show merely the pure data transmission. When a TCP/IP
connection is established via the INSYS GPRS 5.1 serial, data is also generated
(128 byte). The INSYS GPRS 5.1 serial will not terminate a once established con-
nection automatically, i.e. the amount of data for the connection setup may be ig-
nored.
However, the following may occur:

The remote terminal can no longer be reached (power failure in the control
center, system crash, new IP address for the control center, …)

The GSM/GPRS network breaks down temporarily

The GPRS modem has a power cut
In all cases, the INSYS GPRS 5.1 serial will automatically attempt a new connection
setup to guarantee the availability of the application (attempts in intervals of 20s,
80s, 320, 1280s, 1h, 1h, 1h, …).
For the M2M rates, for each (failed) connection setup attempt 1kilobyte amount
of data may be assumed (at a 1 kilobyte matrix); it is therefore recommended to
plan a reserve of 30 to 50 kb up to the according upper limit of the rate.