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Chapter 15 – GPRS Commands  
Multi-Tech Systems, Inc. Wireless GSM/GPRS AT Commands (Document Number S000293I) 
149 
 
Chapter 15 – GPRS commands 
 
Important: GPRS commands are not available under GSM-only software.  
Define PDP Context   +CGDCONT 
Description: 
This command specifies PDP context parameter values for a PDP context identified by the local context 
identification parameter, <cid>.  
 
Four PDP contexts can be defined through the software.  
 
A special form of the set command, +CGDCONT= <cid> causes the values for context number <cid> to 
become undefined.  
 
The test command returns values supported as a compound value. If the modem supports several PDP 
types, <PDP_type>, the parameter value ranges for each <PDP_type> are returned on a separate line.  
 
The read command returns the current settings for each defined context.  
 
The test command returns values supported as a compound value. If the modem supports several PDP 
types, <PDP_type), the parameter value ranges for each <PDP_type> are returned on a separate line. 
Values: 
<cid>   (PDP Context Identifier) a numeric parameter (1-4) which specifies a particular PDP context 
definition. The parameter is local to the DTE-modem interface and is used in other PDP 
context-related commands. 
 <PDP_type>    (Packet Data Protocol type) a string parameter which specifies the type of packet data 
protocol 
• 
IP Internet 
Protocol 
• 
PPP  Point to Point Protocol 
<APN>   (Access Point Name) a string parameter, which is a logical name that is used to select the 
GGSN or the external packet data network.  
 
If the value is null or omitted, then the subscription value will be requested. 
<PDP_address> a string parameter that identifies the modem in the address space applicable to the 
PDP.  
 
 
If the value is null or omitted, then a value may be provided by the DTE during the PDP 
startup procedure or a dynamic address will be requested. The read form of the command will 
continue to return the null string even if an address has been allocated during the PDP 
startup procedure. The allocated address may be read using the 
+CGPADDR command. 
<d_comp>   a numeric parameter that controls PDP data compression 
0   Off  (default if value is omitted) 
1   On  
Other values are reserved. 
<h_comp>   a numeric parameter that controls PDP header compression  
0 
Off (default if value is omitted) 
1   On 
Other values are reserved. 
Notes:
 
 
• 
The data compression algorithm (V.42bis) provided in SNDCP is V.42bis.  
• 
Four CIDs are available to specify four PDP contexts, but only 11 NSAPIs are available for 
PDP activation. Only one can be activated at a time.