26.3.7. Finding the Message Status Values Supported by the +CMGL AT Command in SMS PDU Mode
As mentioned earlier, the +CMGL AT command takes one parameter, message_status. Performing a test operation with the +CMGL AT command allows you to find all message status values that are supported by the message_status parameter. Here is the format of the information response returned after the execution of the test command "+CMGL=?":
In SMS PDU mode, the values inside the above parentheses are integers. The SMS specification has defined five message status values: 0, 1, 2, 3 and 4. They are supported by most GSM/GPRS modems and mobile phones. A description of these five message status values can be found in the earlier section "Syntax of the +CMGL AT Command in SMS PDU Mode".
As an example, here is the response returned from my Nokia 6021 mobile phone to the HyperTerminal program in Windows after the execution of the test command "+CMGL=?":
From above, we know that the Nokia 6021 mobile phone supports all of the five message status values defined in the SMS specification.
Do you remember that we described the format of values inside parentheses in the section "Test Command -- Checks Whether a Certain AT Command is Supported"? If not, you may want to go back and have a look. Here are a few examples showing some of the possibilities: "(0-4)", "(0,1,2,3,4)", "(0,2-4)".
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- 1. Introduction to SMS Messaging
- 2. What Makes SMS Messaging So Successful Worldwide?
- 3. Example Applications of SMS Messaging
- 4. What is an SMS Center / SMSC?
- 5. Basic Concepts of SMS Technology
- 6. Intra-operator SMS Messages
- 7. Inter-operator SMS Messages
- 8. International SMS Messages
- 9. What is an SMS Gateway?
- 10. How to Send SMS Messages from a Computer / PC?
- 11. How to Receive SMS Messages Using a Computer / PC?
- 12. Introduction to GSM / GPRS Wireless Modems
- 13. How to Use Microsoft HyperTerminal to Send AT Commands to a Mobile Phone or GSM/GPRS Modem?
- 14. Introduction to AT Commands
- 15. General Syntax of Extended AT Commands
- 16. Result Codes of AT Commands
- 17. AT Command Operations: Test, Set, Read and Execution
- 18. Testing the Communication between the PC and GSM/GPRS Modem or Mobile Phone
- 19. Checking if the GSM/GPRS Modem or Mobile Phone Supports the Use of AT Commands to Send, Receive and Read SMS Messages
- 20. Operating Mode: SMS Text Mode and SMS PDU Mode
- 21. Setting or Reading the Service Center Address / SMSC Address (AT+CSCA)
- 22. Preferred Message Storage (AT+CPMS)
- 23. Writing SMS Messages to Memory / Message Storage (AT+CMGW)
- 24. Deleting SMS Messages from Message Storage (AT+CMGD)
- 25. Sending SMS Messages from a Computer / PC Using AT Commands (AT+CMGS, AT+CMSS)
- 26. Reading SMS Messages from a Message Storage Area Using AT Commands (AT+CMGR, AT+CMGL)
- 27. Appendix A: How to Choose an SMS Service Provider (SMS Gateway Provider, SMS Reseller, SMS Broker)?
- 28. Appendix B: Comparison Table of SMS Service Providers (SMS Gateway Providers, SMS Resellers, SMS Brokers)
- 29. Appendix C: Free Software/Tools and Libraries for Sending and Receiving SMS Messages with a Computer / PC
- 30. Appendix D: GSM 7-bit Default Alphabet Table (with Character Codes of ISO 8859 Latin 1)