Specifications

Your airtime top-up voucher is typically a long number, and when using this voucher number

with a normal cellphone, you typically need to frame this number by some preceding and

appending text.

For example, with MTN in South Africa, you need to send:

“*141*0000000000000#”

where the “141” is network-dependent, and the 0000000000000 is the voucher number.

This detail is typically provided on the voucher slip.

To send a voucher to the GSM Commander, you simply send it an SMS of the form :

SENDUSD:*141*000000000000# ( from any number)

where 000000000000 is the voucher number.

The GSM Commander will receive this and post the voucher number along to the network.

After a few minutes you can verify if the airtime has been topped up by sending an SMS

containing ATCHECK to the GSM Commander. The device will reply with the current airtime.

9. APPLICATION EXAMPLES

9.1. Example 1: Periodic message

In this example we discuss the use of periodic messages to ensure that your GSM

Commander produces a billable event on the network on a regular basis. If you use a prepaid

SIM card, the network will de-activate your SIM-card if it has not been used for some time

(See Section 5.3).

We will create two behaviour statements, The first will send a free-of-charge “please call me”

message every day, to give you a confirmation that the unit is up and running. The second

will send a Status SMS to your cellphone every 3 days to ensure that the SIM-card remains

active on the network. (The status message also gives you the total airtime remaining)

Configuration:

Using the setup software, we create a behaviour statement that will read as follows:

IF Time Elapsed > 1440 Minutes (24 Hrs)

THEN Send “Please call me” to +27821231234

A second behaviour statement is created, that reads:

IF Time Elapsed > 4320 Minutes (72 Hrs)

THEN Send Status Message to +27821231234

The GSM Commander will count “Time elapsed” as the amount of time that has elapsed since

the last time this statement has triggered, or since the unit has started up.

9.2. Example 2: Monitor alarm

In this example we need to monitor an alarm system, and in the case of an alarm, the GSM

Commander must make a voice call and send a message to one or more numbers.