The present document specifies a profile of AT commands and recommends that this profile be used for controlling Mobile Termination (MT) functions and network services from a Terminal Equipment (TE) through Terminal Adaptor (TA). The command prefix +C is reserved for Digital Cellular in ITU-T Recommendation V.250 [14]. The present document has also the syntax details used to construct extended commands. Commands from ITU-T Recommendation V.250 [14] and existing digital cellular standards (TIA IS-99 [15] and TIA IS-135 [16]) are used whenever applicable. Some of the new commands are defined such way that they can be easily applied to MT of other networks. ITU-T Recommendation T.31 [11] and ITU-T Recommendation T.32 [12] fax AT commands may be used for GSM/UMTS fax transmission from TE. Short Message Service AT commands are defined in TS 27.005. AT commands for packet systems are defined in clause 10 of this specification. The present document assumes an abstract architecture comprising a TE (e.g. a computer) and a MT interfaced by a TA (see Figure 1). The span of control of the defined commands should allow handling of any physical implementation that this abstract architecture may lead to:

• TA, MT and TE as three separate entities;
• TA integrated under the MT cover, and the TE implemented as a separate entity;
• TA integrated under the TE cover, and the MT implemented as a separate entity; and
• TA and MT integrated under the TE cover as a single entity.

The commands described in the present document may be observed on the link between the TE and the TA. However, most of the commands retrieve information about the MT, not about the TA.

Interface between TE and TA is intended to operate over existing serial (ITU-T Recommendation V.24) cables, infrared link, and all link types with similar behaviour. For correct operation many of the defined commands require eight bit data and therefore it is recommended that TE-TA link is set to eight bits/ byte mode. (For infrared operation implementation, refer informative references IrDA. For embedding AT commands and data during on-line data state, refer TIA-617/ITU-T V.80.) Interface between TA and MT is dependent on the interface in the MT. The functional blocks shown in Figure 1, using AT commands, shall follow the principles described in the interactions handling framework TS 23.227.

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

• References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.