Direct Mode Operation; Numbering And Addressing; Figure 3: Direct Mode Operation - Motorola MTP830 S Product Information Manual

20 | Services and Features

Direct Mode Operation

Direct Mode Operation is a mode of simplex operation where radios communicate directly.

Figure 3: Direct Mode Operation

Numbering and Addressing

Each radio has a TETRA ITSI used for addressing the radio over the air interface. However, it is undesirable to
require you to enter a long number to address another radio. To this end, a set of short number schemes can be used.
Alternatively, the radio can be provisioned to treat a short number as an SSI. This scheme can be refined to allow
short dialing within a fleet by combining the ID entered with the radio own SSI.
If the radio is provisioned to treat a short number as a TETRA Short Subscriber Identity (SSI), and the number
entered is less than seven digits, the radio own identity is combined with the number entered to produce the actual
ISSI. Using this scheme, an ISSI can be comprised of a fleet number part and a member part.
The radio own ISSI is used for determining the leading digits for the digits omitted as in the following scenario:
1 The radio has the following ID: 1234567
2 You enter: 890
3 The SSI sent is: 1234890
The following services can use the short SSI for identification for both the called and the calling party:
• Duplex private call
• Simplex private call
• Group call
• Mobile status
• Short data bearer service
• Text message service
Regardless of the short addressing scheme used, if you are provisioned with the capability of entering a real TETRA
ISSI and you enter an ID of seven digits, the number is interpreted as a real TETRA ISSI.
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