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For those interested in background of this question, Please see this question

My Question:

I found a new GSM modem (Wavecom Q24) which does the following in response to AT+CUSD command:

Returns an intermediate OK response. After 2 or 3 seconds(the normal network delay in ussd commands) it gives the actual response. Is this standard behaviour?

Community
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Aqeel Ashiq
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2 Answers2

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No, according to GSM 07.07 the network response should be returned before final result code.

Having said that, I work with Cinterion modules and they have the same behavior as your modem has. They immediately return the result code and later return the network response as an URC. My guess is that they don't want to lock the TA waiting for the network. Instead Cinterion provide a third option to the first argument to cancel a session.

Joonaka
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Each modem which support AT commands return OK when you put AT+CUSD

Sending AT+CUSD without any parameter mean you are asking the modem if it support this command.

you need to add more parameters

AT+CUSD=[<n>[,<str>[,<dcs>]]]

Eg: I'm in Togo the i'm using Togocel SIM card. To check my balance i must use

AT+CUSD=1,"*444#",15

< n > : integer type (sets/shows the result code presentation status to the TE) 0 disable the result code presentation to the TE 1 enable the result code presentation to the TE 2 cancel session (not applicable to read command response)

< str > : string type USSD-string (when parameter is not given, network is not interrogated)

< dcs > : integer type (shows Cell Broadcast Data Coding Scheme, see 3GPP TS 23.038 [25]). Default value is 0.

Samuel
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