Memorandum of SMS Communication

      1. How to establish communication with GSM MODEM
　　You can use terminal emulation software such as HyperTerminal or Pcomm under Windows to directly connect the serial port of the computer with the serial port of the GSM MODEM with a cable.
　　2. Can't communicate with GSM MODEM normally or always appear garbled characters on the emulation terminal
　　Check whether your serial port is guaranteed to be connected normally, the serial port lead of the computer and the serial port lead of the GSM MODEM should be in one-to-one correspondence. The GSM MODEM and the simulated terminal should be set to the same communication rate.
　　But when you use the GSM MODEM for the first time, please set the communication rate on the emulation terminal to 9600bps, 8 data bits, no check bit, and 1 stop bit.
　　3. If you want to get the error code number after the error, you need to set the GSM Modem as follows:
　　AT+CMEE=1
　　4. After sending the short message, if you receive an error message +CMS ERROR 512
　　, it means that your GSM MODEM has received a new short message while sending the short message, and the sending of the short message has been rejected. You need to resend the short message.
　　5. After sending the short message, you receive an error message +CMS ERROR 513
　　and you have encountered one of the following problems:
　　a) Your GSM MODEM has lost the wireless link connection;
　　b) Within 28 seconds after sending the short message, Your GSM MODEM has not received the receiving confirmation from the short message center + CMGS: <sequence number>;
　　c) Within 42 seconds after sending the command to request the establishment of a control channel for sending short messages, your GSM MODEM has not received the base station Confirmation of delivery>.
　　6. After sending the short message, I received an error message +CMS ERROR 514
　　You have encountered one of the following problems:
　　a) The number of the short message center you set is wrong;
　　b) The destination number to which the short message will be delivered is wrong;
　　c) The short message you sent is blocked by the short message center Reject (usually the destination number does not exist or the destination number is disabled).
　　7. After sending the short message, the error message +CMS ERROR 515 is received
　　if your GSM MODEM accepts new commands during initialization or during the execution of commands, this error will occur. You must wait until initialization is complete or instructions are executed.
　　8. How to know that the short message you sent has been delivered to the destination number
　　a) Send
　　in you send short message in text format, your GSM MODEM must be set as follows:
　　at+csmp=49, <X>, <X>, <X>
　　at+cnmi=<X>, <X>, <X>, 1, <X>
　　<X> represents the appropriate parameter you choose according to your needs.
　　After you send the short message, you will receive one of the following two kinds of confirmations from the short message center:
　　+CDS: <X>, <sequence number>, "phone number", "sending time", "received Time", 0
　　or:
　　+CDS: <X>, <Sequence Number>, "Phone Number", "Send Time", "Receive Time", 48
　　The last number in the acknowledgment represents the transmission status of this short message. (0 means that the destination number has been delivered, 48 means that it is impossible to reach the destination number)
　　b) Send in PDU format
　　When you use PDU format to send short messages, your GSM MODEM must be set as follows:
　　at+cnmi=<X>, <X>, <X>, 1, <X>
　　<X> means you need to selected suitable parameters.
　　In the short message in PDU format you want to send, you must set the first byte after the short message center number to 31.
　　After sending the short message, you will receive the following confirmation from the short message center:
　　+CDS : <length> 00 <acknowledgment information in PDU format>
　　Note: In the received acknowledgment in PDU format, the sequence number and transmission status flag exist in hexadecimal numbers, you can directly convert them into decimal numbers number without inverting it before converting.
　　9. How to Send Chinese Short Messages When
　　using the existing GSM MODEM to send Chinese short messages, you must first convert the Chinese short messages to be sent into 16-bit Unicode encoding.
　　A) Send
　　in you send Unicode-encoded Chinese short messages in text format, your GSM MODEM must be set:
　　at+csmp=<X>, <X>, <X>, 8
　　<X> means according to Your needs are the appropriate parameters of your choice.
　　Then you can send the converted Unicode-encoded Chinese short messages in the same way as ordinary text short messages.
　　B) Send by PDU
　　You only need to set the second byte after the destination number string to 08 in your short message in PDU format, and use the
　　converted Unicode-encoded Chinese short message as the send in the PDU The content is sent together.
　　10. How to set up a voice call
　　Send the command ATD <telephone number> to the serial port of the GSM MODEM; <Enter> must confirm that the telephone number is a voice number rather than a fax or data number.
　　11. How to establish a data call
　　First set your GSM MODEM as follows:
　　at+ipr=9600
　　at+ifc=2 , 2
　　at+cbst=0 , 0, 1
　　send the command ATD<telephone number><return to the serial port of the GSM MODEM Car>
　　You must confirm that the phone number is a data number instead of a fax or voice number, and you must confirm that your SIM card has been activated for data communication services.
　　12. How to display the calling phone number when GSM MODEM is called?
　　Set your GSM MODEM as follows:
　　at+clip=1
　　13．When the GSM MODEM is the called party, how to determine whether the calling party initiates a voice, data or fax call?
　　Set your GSM MODEM as follows:
　　at+crc=1
　　14. When the GSM MODEM is called, how to make it answer automatically or not?
　　If you want your GSM MODEM to answer automatically, set your GSM MODEM as follows:
　　ats0=<N> N is the ringing of the GSM MODEM An integer number of times, that is, the GSM MODEM will automatically answer after N rings.
　　If you want your GSM MODEM not to answer automatically, set your GSM MODEM as follows:
　　ats0=0
　　15．How to read or write SMS directly without SIM card
　　Because the SIM card has only 10,000 to 100,000 reading and writing times and storage space for 10-15 short messages, it also involves a certain amount of time to complete the reading and writing of short messages on the SIM card. These factors affect many applications, which require a large amount of data exchange through the GSM network. In order to ensure the smooth progress of the process, the SIM card has to complete a large number of read, write and delete operations, and the life cycle of the SIM card will soon be reached. In addition, the SIM card takes more time to complete these tasks than the outside world requires. In order to solve these problems, it is necessary to make some software settings on the terminal, so that the short message cannot be read and written through the SIM card.
　　The following description describes how to use this method to exchange data between the Falcom A2 series and the data terminal MT4002 without using a SIM card. This method can also be used between 2 MT4002s.
　　a) The RTS signal from the terminal on the serial port can be used to indicate whether the data exchange time slot is busy and the serial port is ready to receive data
　　. b) If both terminals can be used to receive and send short messages, both parties must set the same command when setting and constants.
　　On the receiving end, set the command AT+CNMI=2 , 2, 0, 0, 0
　　On the sending end, set the command AT+CSMP=17, 167, 0, 240 (when sending in PDU format, change 240 to the string DCS (F0))
　　c) When the program finds that the short message is in the format of prefix +CMT followed by the transmitted data, it immediately captures the short message and distributes it to the original address.
　　d) If the sender does not set CSMP=17, 167, 0, 240, the captured short message should have the prefix +CMTI, at this time use the command AT+CMGR=n to read and distribute to the original address, then Use the command AT+CMGD=n to delete this short message to ensure that the SIM card has enough space. Transferred from bbs.sendsms.cn