This European Telecommunications Standard (ETS) specifies a profile of AT commands and recommends that this profile be used for controlling Mobile Equipment (ME) functions and GSM 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.25ter [14]. This ETS has also the syntax details used to construct these extended GSM commands. Commands from ITU-T Recommendation V.25te [14] and existing digital cellular standards (TIA IS-99 [15] and TIA IS-135 [16]) are used whenever applicable. Some of the new commands ar defined such way that they can be easily applied to ME of networks other than GSM. ITU-T T.31 [11] and T.32 [12] fax AT commands may be used for GSM fax transmission from TE. GSM Short Message Service AT commands are defined in GSM 07.05 [24]. This ETS assumes an abstract architecture comprising a TE (e.g. a computer) and a ME interfaced by a TA (see figure 1). The span of control of the defined commands should allow to handle any physical implementation that this abstract architecture may lead to: - TA, ME and TE as three separate entities; - TA integrated under the ME cover, and the TE implemented as a separate entity; - TA integrated under the TE cover, and the ME implemented as a separate entity; - TA and ME integrated under the TE cover as a single entity. The commands described in this ETS may be observed on the link between the TE and the TA. However, most of the commands retrieve information about the ME, not about the TA.