GPRS PPP Link , Authentication

Hello Expertise

I am developing application with EVC++. I have initialized my GPRS modem with the Baud Rate 115200 and I have executed following AT Command AT+CGDCONT = 1,”IP”,”internet”, ,0,0 followed by ATD*99***1. Finally I got message NO CARRIER. I think I missed PPP link and PAP. Please help me how to implement authentication and PPP link? Million thanks in advance
rammuruAsked:
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drelectroConnect With a Mentor Commented:
No I don't understand the problem I'm afraid.

This does not appear to me to be a problem but exepected behaviour.

Your choices are:-

Use the built in PPP stack in wince (very easy)

or

Write your own (very hard (and pointless in your case))

So why not use the built in stack ?

The following may be helpful
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wceoak40/html/cooriDial-UpNetworkingOverview.asp

And
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wcedial/html/cerefrasdial.asp
Shows how to start a dial up networking connection programatically.
Does this help ?

If you really want to implement PPP yourself this where it is defined:-
http://www.faqs.org/rfcs/rfc1548.html

Does that help ?









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drelectroCommented:
what is evc++ ?

What are you trying to plug into your GPRS modem ?
What do you want to do once you're connected ?
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drelectroCommented:
Ahh EVC++ == Embedded Visual C++...

What is your hardware/software  platform ?

IF it's PocketPC (or CE), don't  bother trying to write your own PPP/IP stack pocket PC has a perfectly good one built in.

Just establish a regular dial up connection and dial *99#.
Make sure you configure the modem driver to set the APN in the initialisation string.

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rammuruAuthor Commented:
Hi

I want send data to the host server.  
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drelectroCommented:
What host server ?
What data ?
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rammuruAuthor Commented:
HI Drelectro

No I am using external modem through RS232 COM port.
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drelectroCommented:
Yes I understand that but what is the modem plugged into ?
A PC ?
A Handheld ?
Something else ?
What OS is it running?
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rammuruAuthor Commented:
Hi Drelectro

I am using for Psion Teklogix Handheld terminal. It is wince.net 4.2 OS.
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drelectroCommented:
OK Then you should be able to establish a GPRS connection directly from the handheld you don't need to implement PPP or IP yourself they're built in.

Connecting to GPRS is just like connecting to any other ISP as far as the hand held is concerned.
The only exception is that you must set the APN you want to use before you dial.

Once your connected you can trasfer your data to your server using say FTP or email or whatever you like.
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drelectroCommented:
The following document shows how to configure wince for GPRS

http://www.go.com.mt/wap_phones_setup/ipaq_internet_setup_ir.pdf

The example use IR so you'll need to change that to your com port
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rammuruAuthor Commented:
Hi Drelectro

I have configured already with this method but what I want, through programmatically how do I open com port and send AT commands to connect internet? Up to opening Comport and sending modem initialize command no problem but when I send ATD*99***1# command I am getting message from modem “NO CARRIER”. Any help?
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drelectroCommented:
Is your SIM subscribed for GPRS?
Does the NO CARRIER come immediatly after you send the ATD?
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rammuruAuthor Commented:
Yes my SIM card subscribed for GPRS. When I send ATD*99***1# modem replies Connect 19200 followed by some Jung character (4 or 5 Lines) then finally NO CARRIER.  
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drelectroCommented:
Ahhh I see.

The junk is not junk but PPP, that's exactly what you should expect.

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rammuruAuthor Commented:
Hi Drelectro

I hope now you understand my problem. Any help to solve the problem?
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