Hei,

consider also, that some operators detects silent sms and restores automatically TP-PID and TP-DCS.

Moreover changing TP-PID/TP-DCS I suggest you to use also Message Waiting Indication-Discard option [1].

Some examples:

#pdu='0011000C91'+str(num)+'0000AA0141' # SMS Classic

#pdu='0011000C91'+str(num)+'4000AA0141' # 0x40 (TP-PID)

#pdu='0011000C91'+str(num)+'40C0AA0141' # 0x40(TP-PID) and 0xC0(Message Waiting Indication-Discard)

Cheers,

Luca

[1] http://mobiletidings.com/2009/07/08/voicemail-waiting-indication-sms/

On Mon, May 14, 2012 at 3:27 PM, Chengcheng Gou <gouchengcheng@gmail.com> wrote:
I want to study the Slient SMS, How can it be constructed? Anyone kowns?