Newsgroup: it.tlc.cellulari
Titolo: PPP/ GPRS

I am trying to access my GPRS Modem (Sierra Wireless AirCard 710 -
PCMCIA) programatically. I am facing two problems.
1. The first time I send ATD*99#, I get a CONNECT. Soon after I get a
NO CARRIER. Subsequently whenever I send ATD*99# I get an ERROR.
Cannot get any reason even tho' I have AT+CMEE=2. AT+CEER also does
not return a reason back. What step am I missing? I tried putting an
AT+CGATT=0 and AT+CGACT=0,1 but even tho' I get a detach and a PDP
Context deactivation, ATD*99# still returns ERROR.
2. After CONNECT, the modem sends LCP packets and I am succesfully
able to negotiate LCP. The modem does not send any IPCP or any other
packets after LCP is UP. So I send out an IPCP packet, but the modem
does not respond. Soon after it returns NO CARRIER. What am I supposed
to send after LCP is ACKed?
I am willing to try all possible theories so please send any
suggestions that u have.
Thanks,
Anupama

 NO CARRIER. Subsequently whenever I send ATD*99# I get an ERROR.
You need to setup your GPRS profile, according with your network operator
settings with the command, AT+CGDCONT = "settings".
Or, you can store the right GPRS profile in the card (if this is possible,
this is surely possible with a cell phone like my Ericsson T39m) and then
recall this with the command ATDT*99***numberofprofile#.
Ask your customer care to get the right GPRS setting for your network.
--
Saluti.

Thanks a lot for the follow up. It really helped to get further. Now I
am stuck on the next step - actually the same step in a different
manner.
This is what I do programatically.
I Send the following commands to modem
ATZ
AT+CMEE=2
AT+CGDCONT=1,"IP","APN","0.0.0.0",0,0
AT+CGATT=1
AT+CGACT=1,1
AT+CGDATA="PPP",1
At this point I get an OK instead of CONNECT. What am I doing wrong?
Next if I send ATD*99# or ATD*99***1#, I get the CME Error:
"phone-adaptor link reserved". Again No clue. But if I send
AT+CGPADDR=1, then I get back the IP address assigned to the local
host alright.
If instead of above commands, I send the following
ATZ
AT+CMEE=2
AT+CGDCONT=1,"IP","APN","0.0.0.0",0,0
ATD*99#
Then I get a CONNECT followed by LCP packet. I can successfully get
the LCP layer up and also PAP auth ack. But after that the modem does
not send IPCP Conf Req and neither does it reply to the IPCP Conf Req
that I send out. The result is that after a few seconds I get NO
CARRIER.
Help please...
Thanks a lot,
Anupama

:

[posted via 
phonescoop.com
 - free web access to the alt.cellular groups]

The result is that after a few seconds I get NO CARRIER.
Your SIM is specifically enabled to GPRS ? Ask your customer care and verify
this.
And, the APN string (and the rest of the set-up string) is right ? You need
a specific set-up string to connect with Internet, do not use the string to
set-up the WAP navigation.
--
Saluti.
And so leaving all our hopes and dreams to the wind and the rain.
On the road again, on the road again !

I am using "proxy" as APN. Have been doing so since beginning. Sorry
if "APN" confused you.
The phone is enabled for GPRS. I can connect using Sierra Wireless
Watcher app and also using ATT Mobile Connect for GPRS.
Rephrase of question.
I read in 3gpp specs that TE should send an AT command and after
getting AT response, it should send LCP request and then after getting
ACK for LCP, send out IPCP Req or Auth Req as appropriate.
Which AT command should I send before LCP Req?
I tried 
AT+CGDCONT=2,"IP","proxy",,0,0
AT+CGDATA="PPP",2
and then I send LCP Req. LCP gets ACKed alright. Trouble is that for
IPCP I always get 0.0.0.0 as IP Address. But if I try AT+CGPADDR=2, I
get the 10.x.x.x IP Address alright.
Can't catch the problem. 
I am trying all combinations today again.
Thanks a lot for writing in.
Anupama

 Can't catch the problem.
From Siemens S45 GPRS documentation:
---- init doc ---
ATD*<GPRS_SC>[*[<called_address>]
[*[<L2P>][*[<cid>]]]]#
Request GPRS service
<GPRS_SC>: GPRS Service Code a digit string (value 99)
<called_address> a string that identifies the called party in the
address space
<L2P>: a string which indicates the layer 2 protocol
<cid>: a digit string which specifies a particular PDP
context definition. The cid has to be defined by
using the AT+CGDCONT command
The dial command responds with CONNECT or ERROR
ATD*<GPRS_SC_IP>
[*<cid>]#
Request GPRS IP service
<GPRS_SC>: GPRS Service Code a digit string (value 98)
<cid>: a digit string which specifies a particular PDP
context definition. The cid has to be defined by
using the AT+CGDCONT command
The dial command responds with CONNECT or ERROR
2.5.3 The GPRS dial command ATD
As an alternative to using the GPRS-AT commands it is possible to connect to
a GPRS network by using the dial command "D".
There are two GPRS Service Codes for the ATD command. Values 98 and 99.
e. g.:
ATD*99#
CONNECT // establish a connection via service code 99
ATD*99*123.124.125.126*PPP*1#
CONNECT // establish a connection via service code 99, IP address 123.
//and L2P = PPP and using CID 1.
// The CID has to be defined by means of AT+CGDCONT
ATD*99**PPP#
CONNECT // establish a connection via service code 99 and L2P = PPP
ATD*99***1#
CONNECT // establish a connection via service code 99 and using CID 1
ATD*99*PPP*1#
CONNECT // establish a connection via service code 99 and L2P = PPP and
// using CID 1. The CID has to be defined by means of AT+CGDCONT
ATD*98#
CONNECT // establish an IP connection via service code 98
ATD*98*1#
CONNECT // establish an IP connection via service code 98 using CID 1
// The CID has to be defined by means of AT+CGDCONT
---- end doc ---
The IP assignation over GPRS is due to the settings of network operator, as
can you see in the quoted documentation.
In a normal envirnoment, as can be an european GPRS network like italians
GPRS networks, the IP is _not_ assigned but an IP can be obtained from the
net using the dial command *98#.
The trouble is: the IP assignation is a specific network setting, and can be
or not supported by your network operator.


Thanks for the reply. It worked with 
AT+CGDCONT = 1,"IP","proxy",,0,0
ATD*99#
Negotiated LCP
Negotiated PAP with blank username/ pwd
Negotiated IPCP successfully
Have to now push data to the mobile. But the IP Address that is
assigned is private. Am looking for ways to get around it.
Thanks again...
Anupama