Regarding the difference between sim 300 and sim900 Gsm modem

Hi,

i want to know the difference between sim300 and sim900 gsm modem. I am using sim300 gsm modem in my project and implementated the Project. now Sim300 gsm modem is absolete. Now i have to use Sim900. shall i replace the SIM900 instead of SIM300 as it is. or there is a major difference between sim300 and sim900.

Is there any AT commands changes in SIM900? Please let me know.

Regards,
V. Prakash
Vetal / India

Hello,
Take a look at this, maybe help you:
**broken link removed**

in sim900
1> 3g facilities
2> mms mode service present

Hi,

I had tried the below command AT command to send the sms from my microcontroller:

AT+CMGF=1
AT+CMGS ="9994238372"
Hi (Ctrl+Z)

With the above command in controller to GSM modem via RS-232,
In SIM300 board, the sms is sending. No issue
But in SIM900, the sms is not sending.

But using the Hyperterminal, the same command is working with SIM900 GSM board. but when i send by the command by controller, it is not sending the text. whereas, the SIM300 sending the sms with same controller code.

Please let me know what could be the issue.

Regards,
V. Prakash

refer the document of sim99 as it is different for sim300 in terms of mode set.in sim300 we first set the mode by typing at+cmgf=1(text mode)..so somehow there may be smthing i simm900 mode to set...try it or else send me the simm900 document.

Hi,

AT+CMGF=1
AT+CMGS ="9994238372"
Hi (Ctrl+Z)

The above code is working when i send from Hyperterminal to GSM modem SIM900
But when i connect microcontroller to GSM modem SIM900, sms is not sending.

Please check the sim900 document

Hi,
you should make sure if you are sending this to the SIM formatted correctly to be understood.
Please post the code sending commands.

have u send command AT+CMGF=1 at first

Hi,

Finally, the SIM900 modem works with the below code:

AT+CMGF=1 ( delay of 1 - 2 seconds)
AT+CMGS ="9994238372"( delay of 1 - 2 seconds)
Hi (Ctrl+Z)

Now the issue is, i am sending the five SMS consecutively. so some delay is there while sending the SMS in SIM900.

What happening is, i am sending the first sms. The Modem is waiting for response OK. Without this response, in SIM900, the SMS is not sending. In SIM300, there is no need to wait for response OK. If send the five consecutively, it will send the SMS.

My query is, is there any AT command to avoid this response from the SIM900.


Note: SIM300 Working code:
AT+CMGF=1 (no delay)
AT+CMGS ="9994238372"( no delay)
Hi (Ctrl+Z)

SIM900 Working code:
AT+CMGF=1 ( delay of 1 - 2 seconds)
AT+CMGS ="9994238372"( delay of 1 - 2 seconds)
Hi (Ctrl+Z)

Can u please tell me, is there any command in SIM900 to avoid this delay?
Can i send at+cmgf =1 (without ok response from SIM900, can i send AT+cmgs=”9994238372” command)? In SIM300, no delay is needed.

SIM900 with controller/ PC:
AT+CMGF=1 (pressing ent)
OK ( sending ok response after 1 to 2 seconds delay)
AT+CMGS="9994238372" (Pressing enter)
> ( sending this reponse after 1 to 2 seconds delay)

Can anyone tell me, how to avoid this delay response from SIM900

Regards,
V. Prakash

hi,
the gsm delay is the inbuilt effect made by the simm900 producers.remember we r only using the gsm module...not designing gsm ..if u can made ur own gsm module u can do that.according to the simm 900 specification.delay is required in 1-2 secs for ok.

Hi,

according to the simm 900 specification.delay is required in 1-2 secs for ok.???
I am sending 1 text msg to 10 different mobile number. In that case, I have to nearly wait for 1 minute to deliver all sms to 10 different nos.

for example :For 1st number: At+cmgf=1 after 2 sec delay
OK (response)
At+cmgs="9994238372" after 2 sec delay
> text msg to 1st number (ctrl+Z)

For 2nd number: At+cmgf=1 after 2 sec delay
OK (response)
At+cmgs="8056383722" after 2 sec delay
> text msg to 2nd number (ctrl+Z)
.....................

For 10th number: At+cmgf=1 after 2 sec delay
OK (response)
At+cmgs="9791700246" after 2 sec delay
> text msg to 3rd number (ctrl+Z)

so nearly, i have to wait for 1 min to deliver all the text to 10 different numbers?
This is right? Please tell me know.

Regards,
V. Prakash

hi, the sim900 u r using consist of arm7 prosessor . even if u r using mobile phone to sent same message to 10 persons at a time .....u will notice that one after another the message is being sent.so i mean to say that sim900 company have done programming in arm 7 in this way.