I already used to command a GSM Modem through an application that i programmed in JAVA (Serial communication) in order to send/read SMS.
Now i would like to make an application that send a request to the operator in order to transfer credit from an account to another.
Basiclly in mobile phones, we usually go write something like this ' *220*recipientN°*amount# ' and then confirm and the recipient reseave the amount of credit.
I was wondering what kind of AT-Command to use for such purpose, or is it simply one by sending an sms containing what i just wrote above to accomplish that ?
Thanks in advance.
Related
I would like to process sms messages from my GSM modem (SIM900, but have few others also) but without +CMTI notification.
Code would run in a look and execute various commands, and one of them would be to check if message arrived and then act upon that.
Currently if modem received sms it outpus +CMTI message which get somewhere in the buffer.
Would disabling of that be better approach or should I parse the structure?
Please run
AT+CNMI=0,0,0,0,0
This command silences all SMS URC notifications.
There are pro's and con's with both ways of dealing with receiving and handling SMS messages.
1) Storing on SIM card
There are a couple of downsides with this option. You have to extract the SMS messages from the SIM card which costs time on the one hand. On the other hand it degrades the SIM card itself. Depending on how many SMS's you are receiving this could cause the SIM card to stop working aka no longer able to do read and writes.
2) Handling unsolicited
Here the downside is that you have to be permanently connected to the modem and collect the messages as they come. So if there are USB connection issues it could occur that you lose messages. There are ways of coping with this, for example by configuring the modem so that you manually acknowledge SMS messages received (AT+NACK). This means that the mobile operator network will resend the messages at a later point in time.
When you have modems from different manufacturers then configuration is sometimes a little tricky regarding unsolicited messages. Watch out there if you choose this route. Via AT+CNMI (parameters are different depending on manufacturer/model) you can configure how the modem deals with unsolicited messages. This also involves how the modem handles messages when no "host" is connected to the modem etc... I really recommend finding the AT Command manuals for your modems and seeing what is possible there.
To summarise I personally recommend the unsolicited approach as it's a lot more comfortable handling messages rather than accessing the SIM card to grab and delete received messages.
I was wondering if it is possible to send via GSM protocol and appropriate AT commands, few data through a simple GSM call (witout using data traffic).
For example my system is a PIC + GSM Module and it monitors and processes a string of data.
When the user wishes, he makes a voice call in order to interacts with the GSM module via DTMF commands for example via an APP.
My dubt is if the GSM module is able to send the data to thesmartphone in order to monitor the status of the system. The module is a Quectel M95.
During some investigation, I saw that the module can send USSD codes but I don't know if it's possible to customize the USSD and read it from the smartphone as I wish.
Or maybe is it possible to use the FAX for data exchange?
Thanks everybody in advance
Marco
There are a couple of alternatives if you want to avoid using data traffic. But they all require either a connection to a service that is capable of receiving SMS's for example Twilio. Or you can of course have a GSM Module connected to your server which could do the receiving.
You could then send your data and requests for data within an standard SMS body. Or alternatively you could send binary SMS's where you are not limited to the 7 bit character set.
USSD would only work if you have a USSD service provider (I think Twilio has this now). Because the USSD service must initiate a USSD session for your target GSM Module to respond to. USSD code sending for GSM Modules is operator specific and therefore you are limited to what they have implemented (usually for prepaid users and the topping up of accounts).
Is there any way to initiate an SMS MO from a device from the network. Eg: Can I send a special USSD push to a device from the network so that it will SMS a specified text to a specified number from the device.
Only if you are the network operator and the USSD message is defined in the network and supported by the device.
You could also send a MT SMS and get the specified text as a reply (again supported on the device, obviously).
This largely depends on the device capabilities. The device needs logic for processing the USSD message, instead of just displaying it, and to trigger sending the MO SMS.
Since this is not a factory configuration, you would need a custom application to be installed on the device, provided that the device platform allows for the needed functionality. For example some J2ME-capable devices do have this functionality. Consult your device manufacturers development documentation.
I have my servlet that has a method that randomly generates passwords. I want it to be able to send each generated password to a specified phone number. What do I need to do? I read somewhere that it is possible using a GSM modem which I have. Any one tell me how to interface the servlet and the modem to send the sms
Here; this shows how to send SMS from modem using AT commands. You can use it in your servlet.
I have an SMS Appliaction, which receives the messages through GPS Modem and revert back through GPS Modem. The Modem is using COM1.
Now, i need two more appliactions which can send messages through the same GPS Modem. I tried making a webservice which can access the COM1 to send data, but when i try to connect through webService, it throw an error saying, 'COM1 is already occupied, Access denied.'.
Can anybody help me to connect through the modem in above scenario.
Khushi
You have to make sure only 1 connection is made.
Easiest (and most low-tech, but probably most flexible) is having a script checking a directory for files regularly and sending the messages in the file to the modem. The webservice then just writes a file for every SMS it received. (this can be trivially extended to accept emails, web requests, etc, ...)
A bit more sophistacated is to start a thread to do the communication and push the messages on a FIFO like datastructure provided by your favorite programming platform. A BlockinQueue would be perfect. The thread reads the messages from the queue and sends them to the GSM modem.
If you want to have confirmation the SMS is sent (which in my experience does not mean anything and certainly not that the recipient actually received it) you'll need to find a way to return feedback to the caller. This can be as simple a setting a boolean flag in the message to sending another message or performing a callback. But I would not bother. I had situations where 30% of messages dissapeared even when we had confirmation of the message central.