SIM900( receive text message)

[Sheep]

When i want to send a text SMS to my sim900 module,i found my module can not recognize the text SMS immediately.But it can recognize the text SMS after I make another call to my module.I do not know why.Maybe my module is just sleeping,and what will i do.
Thanks for your help.

 

[kabeer02]

It could be a network problem from your service provider

 

[Sheep]

I found the reason.I send and receive SMS through code with serial port in LINUX. I keep always send a AT command to port with 2s to keep port awake,I can receive a SMS immediately after that.And if you want to send a SMS through the code,the character 'CTRL+Z' should be represented as '\x1a' rather than '0x1a' in program design.