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Siemens Brodersen MC55 AT User Manual

Page 345

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MC55_ATC_V04.00

Page 345 of 475

3/17/06

Confidential / Released

• If writing fails due to timeout, then

AT^SM20

=1 causes "+CMS ERROR: Unknown error" to be returned;

AT^SM20

=0 causes "+CMS ERROR: timer expired" to be returned.

• Note that some providers do not recognize an @ symbol used in a short message. A widely used alternative

is typing "*" as defined in GSM 03.40 (GPP TS 23.40).

• For baudrates lower than 19200 it is recommended to use the line termination character only (refer to

ATS3

=

, default

) before entering the text or PDU. Use of the line termination character followed by the

response formating character (see

ATS4

=

, default

) may cause problems.

• SMS-COMMANDs and SMS-STATUS-REPORTs cannot be stored in text mode.
• All characters entered behind the ">" prompt will be recognized as GSM characters. For example, "Back-

space" (ASCII character 8) does not delete a character, but will be inserted into the short message as an addi-

tional physical character. As a result, the character you wanted to delete still appears in the text, plus the GSM

code equivalent of the Backspace key.

• Message Length in Text Mode

The maximum length of a short message depends on the used coding scheme: It is 160 characters if the 7

bit GSM coding scheme is used, and 140 characters according to the 8 bit GSM coding scheme.

In case UCS2 character set selected it is highly recommended to set Data Coding Scheme (

of

AT+CSMP

) to 16-bit data, otherwise the length of sms user data is restricted to 88 octets. Even better for mes-

sages with UCS2 character set is the PDU Mode.

• The length of 8-bit data coded short messages has to be greater than 0.