incoming sms to modem - what format

incoming sms to modem - what format - fields?

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ColinK - 24 Jun 2007 23:08 GMT

Hi

I have not yet set up a modem to receive incoming sms. I am trying to
understand the string of text / fields that will be available from the
modem.

Using AT commands I intend to access an external gsm modem connected
to the computer
At this stage I think all I need is the SenderID (mobile No) and the
incoming message which I intend to forward to a server.

Could someone give me examples of all the parameters / fields, in
their exact order that I am likley to extract from the modem / sim, so
that I can give some consideration as to how I will filter out the
unrequired fields.

Better still, if I could send some test sms's to someone's modem and
they could email the full message to me I would appreciate it.

Thanks Colin K
PS I have probably overlooked some points or have too narrow an
understanding of what I want - please feel free to educate me.

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John Henderson - 25 Jun 2007 00:39 GMT

> I have not yet set up a modem to receive incoming sms. I am
> trying to understand the string of text / fields that will be
[quoted text clipped - 18 lines]
> an understanding of what I want - please feel free to educate
> me.

One of the first decisions you need to make is the protocol
you're going to use between modem and your application. The
alternatives (not necessarily both supported by every modem)
are text-mode and PDU-mode.

The advantage of text-mode is that the translation from PDU
(Protocol Data Units) to ASCII text is done for you by the
modem. The disadvantage is that the modem might not get this
right, or do it completely, especially if the incoming SMS
contains something clever (an "enhanced" EMS message, 8-bit
encoding, etc). You'd need to see exactly how it handled
concatenated (multi-part) messages, for example.

PDU-mode is going to mean more programming, but give you
complete control over your application.

You could start with some relevant GSM standards. I'd recommend
GSM 03.38, 03.40, 07.05 and 07.07.

This is a good introduction to PDU-mode:
http://tinyurl.com/ywmcgn

John

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ColinK - 25 Jun 2007 01:04 GMT

> > I have not yet set up a modem to receive incoming sms. I am
> > trying to understand the string of text / fields that will be
[quoted text clipped - 43 lines]
>
> - Show quoted text -

Hi John

Thanks for your prompt response.

I have had a quick look at the Siemens doc and will read in more
detail at some stage.

My messages incoming messages are all likely to be short plain text
messages (plus presumably occasional spam and worng numbers), so using
PDU mode will probably be best to ensure I get the correct data to
process.

I will probably purchase a well known brand of modem, eg Siemens, 9I
have looked at a MC35) and will check to ensure it supports PDU mode.

Can you recommend where I could get any script (to get me started) ,
that might suit PDU mode; preferably PHP

Any other recommendations / information would be appreciated.

Thanks ColinK

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John Henderson - 25 Jun 2007 03:28 GMT

> I have had a quick look at the Siemens doc and will read in
> more detail at some stage.
[quoted text clipped - 3 lines]
> numbers), so using PDU mode will probably be best to ensure I
> get the correct data to process.

At the end of this post is the log of a modem session to show
you the difference between text-mode and PDU-mode. The
"AT+CMGF=1" commands switches the modem into text-mode, while
"AT+CMGF=0" selects PDU-mode. The "AT+CMGR=4" command simply
reads message number 4. I have manually line-wrapped the PDU
to 60 characters.

> I will probably purchase a well known brand of modem, eg
> Siemens, 9I have looked at a MC35) and will check to ensure it
> supports PDU mode.

Be aware that Siemens has sold its GSM business to Benq of
Taiwan, and I don't know what the quality or support situation
now is. A pity, because the German stuff was excellent.

I'm using a Wavecom "Fastrack" 1206b modem, but I don't know if
that model is still available. Wavecom has a good reputation,
but one of their idiosyncrasies is the strong recommendation
that the modem is reset periodically. There's even a command
to automate this, but you need to be aware that you might need
to reissue some configuration commands when this happens.

> Can you recommend where I could get any script (to get me
> started) , that might suit PDU mode; preferably PHP

There's probably some out there, but I've never looked. I've
always written my own code (not PHP though). If you get stuck,
get back to me.

John

AT+CMGF=1
OK
AT+CMGR=4
+CMGR: "REC READ","+61405104946",,"01/12/15,14:08:51+44"
UEL security trading for week ending 14/12/01
Open:$2.540
Last:$2.420
High:$2.540
Low:$2.410
Vol:2,619,094
AllOrds:3,238 -75
Infra Utils:2,654 -46

OK
AT+CMGF=0
OK
AT+CMGR=4
+CMGR: 1,,153
07911614051145F6040B911604154049F600001021514180154499D52213
342F8FEBF2343D0FA2CBC3E4B4FB0C32BFE5A07BB9BC0695DDE4B4FB0C8A
D15E31D90B166B289EF0B25B2790B96A345843C10CCFE93A81CC4593C11A
0A64FA8CD60964AE1A0DD65030DF779D40E6A2C5600D85F5CDD6C958B658
8E05CBD11A8A209BFD9493E7BA194B36C3815AB75A4391749BE56150959E
66CF753296AD4603B56836

OK

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Andreas Hezel - 26 Jun 2007 15:06 GMT

John Henderson schrieb:

>> I have had a quick look at the Siemens doc and will read in
>> more detail at some stage.
>
> Be aware that Siemens has sold its GSM business to Benq of
> Taiwan, and I don't know what the quality or support situation
> now is. A pity, because the German stuff was excellent.

Thats not completely correct. Siemens sold the consumer CellPhone
Department but not the WirelessModules Division for automotive and
industrial purposes.

see:
https://pia.khe.siemens.com/index_wireless_modules-14197.htm

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Andreas Hezel
__________________________________________________________
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Andreas Hezel ---> Mail: AndreasHezel@gmx.de
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Reply to this Message

John Henderson - 26 Jun 2007 21:23 GMT

> John Henderson schrieb:

>> Be aware that Siemens has sold its GSM business to Benq of
>> Taiwan, and I don't know what the quality or support
[quoted text clipped - 7 lines]
> see:
> https://pia.khe.siemens.com/index_wireless_modules-14197.htm

Thanks for that information - it comes as a nice surprise to me,
as I've always found Siemens equipment very well-designed and
reliable.

John

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John Henderson - 25 Jun 2007 07:36 GMT

> My messages incoming messages are all likely to be short plain
> text messages (plus presumably occasional spam and worng
> numbers), so using PDU mode will probably be best to ensure I
> get the correct data to process.

I should make special mention of "€", the Euro currency symbol.
If you want to render it correctly from incoming SMSs into
something like utf-8 (as I'm posting in), you'll need to use
PDU-mode. This is because it has no ASCII equivalent for the
modem to convert it to (in text-mode, the modem should convert
it to ASCII "e" instead - see GSM 03.38).

In fact GSM 03.38 has two tables for the characters used in the
default 7-bit alphabet. At 128 possibilities, 7 bits just
doesn't provide enough characters. So a few GSM characters are
consigned to an extension table, and one special character in
the first table just indicates that a second-table character
follows. So each of these second-table characters always uses
up two PDU character positions.

These characters are:

€ | ^ { } [ ] ^ \

Note that most are ASCII characters. Whether a modem renders
any of them correctly in text-mode will be a matter for
experiment.

John

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