GPRS config wierdness

[Dave Royal]

I now have an Italian Wind prepaid SIM (thanks Donald for the tip).

Before configuring dial-up networking (PPP) on my Zaurus PDA (connected
via bluetooth) I entered the AP (internet.wind) into my Nokia 6310i
phone under the 'GPRS modem' settings.

But if I then set the PDA to dial ATDT*99# (or ATDT*99***1#) the
connection fails with an error which depends on which UK provider I'm
connected to:
With Orange: "Subscribe to GPRS first"
With T-mobile: "Access point not valid"

The PPP log just says "LCP terminated by peer"

Googling around most people say I should this init string:
AT+cgdcont=1,"IP","internet.wind"

And it's true - I do this and it works. End of problem (except I can't
see why the first method didn't work since AFAICS it's just an
alternative way of setting the AP.)

So then I configure Win/XP to use same phone with GPRS and it works fine
with just dialling *99# I do not need to put the AP name into the PC.

Any ideas what causes the local provider to generate those messages, or
why the PDA needs the init string and WinXP doesn't? Just curious.

Dave
--
(Remove any numerics from my email address.)

[John Henderson]

Dave Royal wrote:

> I now have an Italian Wind prepaid SIM (thanks Donald for the
> tip).
>
> Before configuring dial-up networking (PPP) on my Zaurus PDA
> (connected via bluetooth) I entered the AP (internet.wind)
> into my Nokia 6310i phone under the 'GPRS modem' settings.
>
> But if I then set the PDA to dial ATDT*99# (or ATDT*99***1#)
> the connection fails with an error which depends on which UK
> provider I'm connected to:
> With Orange: "Subscribe to GPRS first"
> With T-mobile: "Access point not valid"
>
> The PPP log just says "LCP terminated by peer"
>
> Googling around most people say I should this init string:
> AT+cgdcont=1,"IP","internet.wind"

This command (the setting of a PDP context) needs to be done
once only (unless the non-volatile memory ever gets erased).
Having been done, it can be removed from the init sequence in
future.

It specifies the type of packets ("IP") as well as the APN for
context ID number 1, which is the default ID for "ATD*99#" and
the context "1" specifically requested in "ATD*99***1#".

If you were to now try "ATD*99***2#" for dialling, I'd expect
those errors again until you'd defined the PDP context for
context ID 2 with 'AT+CGDCONT=2,"IP","internet.wind"'.

> And it's true - I do this and it works. End of problem (except
> I can't see why the first method didn't work since AFAICS it's
> just an alternative way of setting the AP.)
>
> So then I configure Win/XP to use same phone with GPRS and it
> works fine with just dialling *99# I do not need to put the
> AP name into the PC.
>
> Any ideas what causes the local provider to generate those
> messages, or why the PDA needs the init string and WinXP
> doesn't? Just curious.

As above, it works because you've set the PDP context
previously.

John

[Dave Royal]

John Henderson wrote:
> Dave Royal wrote:
>
>> I now have an Italian Wind prepaid SIM (thanks Donald for the
>> tip).
>>
>> Before configuring dial-up networking (PPP) on my Zaurus PDA
>> (connected via bluetooth) I entered the AP (internet.wind)
>> into my Nokia 6310i phone under the 'GPRS modem' settings.
>>
>> But if I then set the PDA to dial ATDT*99# (or ATDT*99***1#)
>> the connection fails with an error which depends on which UK
>> provider I'm connected to:
>> With Orange: "Subscribe to GPRS first"
>> With T-mobile: "Access point not valid"
>>
>> The PPP log just says "LCP terminated by peer"
>>
>> Googling around most people say I should this init string:
>> AT+cgdcont=1,"IP","internet.wind"
>
> This command (the setting of a PDP context) needs to be done
> once only (unless the non-volatile memory ever gets erased).
> Having been done, it can be removed from the init sequence in
> future.
>

Doesn't seem to work in my case. I just removed the init string from the
Zaurus and tried both *99# & *99***1# - both gave the error message
above on the phone. Put the init string back and it works.

> It specifies the type of packets ("IP") as well as the APN for
> context ID number 1, which is the default ID for "ATD*99#" and
> the context "1" specifically requested in "ATD*99***1#".
>

This PDP type "IP" seems to be the only bit of data provided by my init
string that I can't put into the phone itself (which only allows APN).
OTOH I read that "IP" is the /only/ PDP type there is, so maybe the
phone just assumes that.

> If you were to now try "ATD*99***2#" for dialling, I'd expect
> those errors again until you'd defined the PDP context for
> context ID 2 with 'AT+CGDCONT=2,"IP","internet.wind"'.
>
>> And it's true - I do this and it works. End of problem (except
>> I can't see why the first method didn't work since AFAICS it's
>> just an alternative way of setting the AP.)
>>
>> So then I configure Win/XP to use same phone with GPRS and it
>> works fine with just dialling *99# I do not need to put the
>> AP name into the PC.
>>
>> Any ideas what causes the local provider to generate those
>> messages, or why the PDA needs the init string and WinXP
>> doesn't? Just curious.
>
> As above, it works because you've set the PDP context
> previously.
>
> John

I suppose the difference in behaviour of the Zaurus (runs Linux) and the
WinXP box may just be down to differences between pppd on the Z and
whatever WinXP's equivalent is. When I get the error message pppd seems
to be happily negotiating with a server and exchanging IPCP packets when
it gets:

rcvd [LCP TermReq id=0x2] (or sometimes 0x1)

Anyway, thanks for information John. It gives me something - "PDP
context" - to research further.

[John Henderson]

Dave Royal wrote:

> Doesn't seem to work in my case. I just removed the init
> string from the Zaurus and tried both *99# & *99***1# - both
> gave the error message above on the phone. Put the init string
> back and it works.

Interesting - I haven't seen a device before which fails to keep
the context setting in flash memory.

> This PDP type "IP" seems to be the only bit of data provided
> by my init string that I can't put into the phone itself
> (which only allows APN). OTOH I read that "IP" is the /only/
> PDP type there is, so maybe the phone just assumes that.

"X.25", "IP", "IPV6", "OSPIH" and "PPP" are defined in the
standard (3GPP 27.007). It may well be that only "IP" has a
real-world cellular implementation at present. 3GPP 27.007
says that implementation of the "AT+CGDCONT" command itself is
optional for devices supporting ony a single packet type.

> I suppose the difference in behaviour of the Zaurus (runs
> Linux) and the WinXP box may just be down to differences
> between pppd on the Z and whatever WinXP's equivalent is. When
> I get the error message pppd seems to be happily negotiating
> with a server and exchanging IPCP packets when it gets:
>
> rcvd [LCP TermReq id=0x2] (or sometimes 0x1)
>
> Anyway, thanks for information John. It gives me something -
> "PDP context" - to research further.

Also interesting, as I use Linux almost exclusively. And I've
never needed "AT+CGDCONT" with it or Windows since the initial
setting years ago (both on a Siemens phone and a Wavecom
modem). Like you, I'd read that "AT+CGDCONT" is needed in the
init string, but noone had reported a problem when I'd
previously suggested it could be removed subsequently.

John

[Dave Royal]

John Henderson wrote:
> Dave Royal wrote:
>
>> Doesn't seem to work in my case. I just removed the init
>> string from the Zaurus and tried both *99# & *99***1# - both
>> gave the error message above on the phone. Put the init string
>> back and it works.
>
> Interesting - I haven't seen a device before which fails to keep
> the context setting in flash memory.
>

I normally send this sequence to the phone from the PDA:
ATZ
AT+cgdcont=1,"IP","internet.wind"
ATDT*99#

In the test referred to above I removed the AT+cgdcont... but left the
ATZ - I had forgotten that ATZ means 'reset'. If I remove ATZ as well it
works - with just ATDT...

I infer that ATDT causes the phone to forget the PDP context - and also
probably to not use the APN I've configured in the phone itself.

[John Henderson]

Dave Royal wrote:

> I normally send this sequence to the phone from the PDA:
> ATZ
> AT+cgdcont=1,"IP","internet.wind"
> ATDT*99#
>
> In the test referred to above I removed the AT+cgdcont... but
> left the ATZ - I had forgotten that ATZ means 'reset'. If I
> remove ATZ as well it works - with just ATDT...
>
> I infer that ATDT causes the phone to forget the PDP context -
> and also probably to not use the APN I've configured in the
> phone itself.

Now we're getting somewhere!

There are two types of reset. "ATZ" resets to user defaults,
while "AT&F" resets to factory defaults.

I haven't seen a device before which undoes the PDP context with
an "ATZ" command. But it does make sense.

Having set the device up the way you want it, you should be able
to save your user defaults with the "AT&W" command (so that
"ATZ" simply restores them).

John