Geeetech

Hello,
I have bought a few days ago a SIM900 shield. I am using it with a Arduino Mega. I can send to the SIM900 AT commands and I have the answer from the SIM900.
However, my shield cannot connect to any network. I have tried a lot of SIM cards from different operators and from different places and with sereral power sources (even a professional electronic one). The LED is always blinking quickly.

Here is a strange thing :
AT+COPS=?
+COPS: ,,(0,1,4),(0,2)
I have no network detected even if I am in a good place where my old GSM cellphone got network quite well with the same operator.

Here is another strange thing :
AT+CBAND?
+CBAND: INVALID_BAND_MODE,ALL_BAND

I think INVALID_BAND_MODE is not normal. I have tried to force the band with all possible values but the shiels doesn't connect to any network. More, everytime I start the shield, INVALID_BAND_MODE come back...

Any idea of the problem ?

Hi,
It is not working.
The LED is always blinking quickly (800ms) event after a lot of time.
When I send "AT" command, I have "OK" answer.
Concerning
-------------------------------
AT+COPS=?
+COPS: ,,(0,1,4),(0,2)
--------------------------------
I have always this result, whatever the SIM card.
My power supply is 5V/3A so I respect the requirements...
ATD88888888888; gives me "NO CARRIER"

Hello,
Thank you for this answer but please, stop with this questions. I know electronic, I know to read tutorials and documentations on the Internet. Everything is ok concerning jumpers, power supply,...
If I write questions on this forum, this is because I have tried all I have found, and I know that there is a lot of answers concerning SIM900 on the Internet.
Mine doesn't work and you said to me, via eBay, to send a message on this forum... If you don't have the solution, write it instead of writing this kind of anwser.
Thank you

Dear friend,
I am so sorry that we haven't help you solve the problem in our previous comminication. Our technical team had discussed your problem a couple of days and found out the solution.
If you use the Router rather than Modem or Exchanger before networking test for GPRS module , pay attention to the following steps.
1. Set a Fixed IP for your computer.
2. Set Port Mapping on the Rooter and Mapping the Port to your IP. Range of Port Mapping is between 0 and 65535.
Could you please have a try?
We will update the specific networking test steps in our WIKI soon.
Sincerely sorry again for the inconvenience and hope it will be solved soon.
Best regards.

Hi,

I don't understand what you are talking about.

What is the relation ship with a ip router and gsm shield?


can you be specific and and tell us what exactly we have to do wit the shield.

As far as i can see, onto that forum at least we are 3 people habing the same problem and there is no clear solution at the moment.

Regards,

Dear friend,
Q1. Why need to specify ‘Local Host Port’ on the Router(Port Mapping)?
ADSL dial through a router and host share network by router. In this case, host usually extracts Private IP such as 192.168.x.x. Then specify ‘Local Host Port’ on the Router(Port Mapping) is necessary and forwarding Port to corresponding Local Host , then Internet application can access the Local Host through this Port.

Q2. Why need to specify a Fixed Private IP for the Local Host?
Port Mapping is one-to-one. If the Local Host is specified to obtain IP automatically, the IP address will change when the computer restarts or reconnects to the network. Hence, it is necessary to specify a Fixed Private IP .

We had already sorted out the Chinese version, the English version isn't avaiable now. We will publish on our wiki after we finish.
Could you please be patient and wait a moment? Thanks in advance. Best regards.

Hi,


I Still do not understand.

We are talking about GSM Shield with no GSM signal so we are unable to connect to the GSM provider and to regsiter to its network (and that is not IP network we are talking about).

We are not talking about IP or GPRS an not talking about internet connection.


On my case, there is no IP router and it is a standalone project.

So it seems that our answer has nothing to do with our problem.

I am a little fed up with that as i already use this king od sheild from varius providers, an it is working fine,

ours are just not working and according to what i can see, we are several people with the same issue.