GSM Channel Mode Modify和Channel Mode Modify Acknowledge信令

最近研究了下如何通过GSM Channel Mode Modify和Channel Mode Modify Acknowledge信令，获知GSM终端支持的data Rate

思路与原理：

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I
n

an RR connected state, acknowledges a CHANNEL MODE MODIFY message by sending a CHANNEL MODE MODIFY ACKNOWLEDGEMENT message specifying and switching to the correct mode.

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- the new mode if that mode is supported.

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- the old mode if the new mode is not supported
.

相关信令：

Step	Direction	Message
1	SS->MS	PAGING REQUEST TYPE 1
2	MS->SS	CHANNEL REQUEST
3	SS->MS	IMMEDIATE ASSIGNMENT
4	MS->SS	PAGING RESPONSE
5	SS->MS	CHANNEL MODE MODIFY
6	MS->SS	CHANNEL MODE MODIFY ACKNOWLEDGE
7	SS->MS	CHANNEL MODE MODIFY
8	MS->SS	CHANNEL MODE MODIFY ACKNOWLEDGE
9	SS->MS	CHANNEL MODE MODIFY
10	MS->SS	CHANNEL MODE MODIFY ACKNOWLEDGE
11	SS->MS	CHANNEL MODE MODIFY
12	MS->SS	CHANNEL MODE MODIFY ACKNOWLEDGE
13	SS->MS	CHANNEL MODE MODIFY
14	MS->SS	CHANNEL MODE MODIFY ACKNOWLEDGE
15	SS->MS	CHANNEL RELEASE

在PDU Manager中的channel mode decode如下：

0 - Signalling Only (0x0)

1 - Speech Full Rate or Half Rate Version 1 (0x1)

33 - Speech Full Rate or Half Rate Version 2 (0x21)

65 - Speech Full Rate or Half Rate Version 3 (0x41)

129 - Speech Full Rate or Half Rate Version 4 (0x81)

130 - Speech Full Rate or Half Rate Version 5 (0x82)

131 - Speech Full Rate or Half Rate Version 6 (0x83)

3 - Data, 12.0 Kbit/s Radio Interface Rate (0x3) 9600 bps

11 - Data, 6.0 Kbit/s Radio Interface Rate (0xB) 4800 bps

19 - Data, 3.6 Kbit/s Radio Interface Rate (0x13) 2400 bps