Technical information about GSM

For technical support and advanced users

v4.20 - DD / COM One - December 2000

 

1.     Introduction. 3

1.1       Products concerned. 3

1.2       OEM... 3

1.3       Cellular standards. 3

2.     Transparent mode, non transparent mode (= RLP), and UDI. 3

2.1       Notes for ISDN.. 3

2.2       Notes. 4

2.3       Note for France. 4

3.     Compression done by PC Card through GSM network. 4

3.1       Data compression modes. 4

3.2       Speed transfer benchmark. 4

3.3       Notes. 5

4.     Errors correction support 5

5.     Connection and carrier : information's returned by S95. 5

5.1       Register S95=1. 5

5.2       Register S95=44. 5

5.3       Register S95=45. 5

6.     GSM modes : connections traces samples. 6

6.1       Non Transparent (RLP, default PC Card mode) 6

6.2       Transparent only (not recommended) 6

6.3       Transparent + compression V42bis and errors correction. 6

6.4       Transparent + compression MNP5 and errors correction. 6

6.5       UDI non transparent 7

6.6       UDI transparent  (not recommended) 7

7.     Fax class. 7

7.1       Note : 7

8.     Dialling. 7

8.1       Maximum digits. 7

8.2       Pauses / calling tone. 7

9.     COM One company. 8


 

1.     Introduction

1.1     Products concerned

This document applies to these PC Cards :

 

- MC218 (COM One Communication Card, 3 in 1).

- MC220 (COM One Platinium Card, 4 in 1).

- MC222 (COM One Platinium Card, 2 in 1).

- MC223 (COM One Platinium Card, 3 in 1).

- GSM Only (COM One GSM/PCN/DCS Mobile Data PC Card).

1.2     OEM

Most of the information's of this document are true for OEM products too.

 

1.3     Cellular standards

 

Standard

Max speed in Bits per second

Kb/s (Kilo bytes per second)

V34 (analog)

33 600

3,28

GSM

9 600

0,93

HSCSD

57 600

5,62

GPRS

150 000

14,6

 

2.     Transparent mode, non transparent mode (= RLP), and UDI

 

Transparent

AT+CBST=x,x,0

Non transparent

AT+CBST=x,x,1

Fax

UDI

AT+CBST=[65 to 71],x,x

(we recommend 71)

Possible

Possible

Not available

Non UDI

AT+CBST=[<65],x,x

(we recommend 7)

Possible

Possible

Not available

 

UDI = Unrestricted Digital Information.

RLP = Radio Link Protocol.

You can get more information's about AT +CBST into the reference manual.

2.1     Notes for ISDN

- By default we use the non transparent mode (= RLP). String is : "AT +CBST=7,0,1"

- For some rare numbers the string "AT +CBST=71,0,1" may be recommended. The GSM network moves the connection to a digital link to the digital telecom network, and avoid the analog usual way through 2 analogs modems.

- If you know the server is using an ISDN TA (V120). You can use the string: "AT +CBST=71,0,1". You may get a fast connect (5 seconds instead of 20 for analog). Some people call it "V110" but this has nothing to do with the ISDN V110 protocol. We prefer to name this mode "UDI".

- You can receive calls from an ISDN TA in UDI mode. But your GSM data subscription must validated for UDI (ex: France Telecom Itineris need this).

2.2     Notes

- In PSTN and/or without the GSM cable plugged, MC218 ignore the AT +CBST command but MC22x return "ERROR".

- "AT \N0" is a fast command to set transparent mode. "AT \N2" for RLP. But we recomment to use the command "AT +CBST…", it is more clear.

2.3     Note for France

- In some areas of France, the SFR network requires the "AT+CBST=7,0,1" to be sent a second time (this command is already sent by default).

- Minitel : AT+CBST=71,0,1 (note that this is *not* the analog V23 mode, it's a digital mode).
Minitel GSM speed is 9600 bps instead of the 1200/75 bps analog mode.
Only France Telecom Itineris enable access to UDI (Minitel ...). SFR don't provide UDI service.

3.     Compression done by PC Card through GSM network

 

MC218

MC220, MC222, MC223

GSM Only card

Transparent mode

Not possible

Yes

Yes

UDI

Not possible

Not possible *

Not possible *

Non Transparent mode

Not possible

Not possible *

Not possible *

 

* : Not supported by networks yet.

3.1     Data compression modes

MNP4 + V42bis

MNP4 + MNP5

AT \N5 %C2

AT \N5 %C1

 

These commands automatically switch to the right mode (transparent). The opposite command could be : AT+CBST=7,0,1.

We recommend using MNP4 + V42bis instead of MNP4 + MNP5.

3.2     Speed transfer benchmark

Downloading from an internet connection by FTP a HTML file (40415 bytes).

- PSTN 31200 bps no compression (%C0) : 3173 bytes / sec.

- PSTN 31200 bps MNP4 + V42bis : 8252 bytes / sec.

- Cellular 9600 bps RLP : 937 bytes / sec.

- Cellular 9600 bps MNP4 + V42bis : 1800 bytes / sec.

3.3     Notes

With compression mode, the error correction is activated only after been connected with the modem. That's why if any little GSM network error occurs during the negotiation, the connection can fail ("NO CARRIER").

4.     Errors correction support

GSM Mode

Without compression

With compression

Transparent mode

No errors correction

Yes done by the PC Card

UDI

Yes, done by the network

Not possible

Non Transparent mode

Yes, done by the network

Yes by V42 bis

5.     Connection and carrier : information's returned by S95

This register can be set to various values, and is very useful to get more information's about the connection (for GSM and PSTN modes only).

5.1     Register S95=1

AT S95=1

OK

atdt0556693080

 

CONNECT 9600

5.2     Register S95=44

ATS95=44

OK

atdt0556693080

 

CARRIER 9600                 <- DCE speed (connection)

 

PROTOCOL: RLP

 

COMPRESSION: NONE

 

CONNECT 115200               <- DTE speed (junction)

5.3     Register S95=45

ATS95=45

OK

atdt0556693080

CARRIER 9600                 <- Line speed

 

PROTOCOL: RLP

 

COMPRESSION: NONE

 

CONNECT 9600                 <- Line speed

6.     GSM modes : connections traces samples

6.1     Non Transparent (RLP, default PC Card mode)

atS95=44

at+CBST=7,0,1

OK

atd0556788382

CARRIER 9600

 

PROTOCOL: RLP

 

COMPRESSION: NONE

 

CONNECT 115200

6.2     Transparent only (not recommended)

atS95=44

OK

at+CBST=7,0,0

OK

atd0556788382     (COM One BBS, modem 33600)

CARRIER 9600

 

PROTOCOL: NONE

 

COMPRESSION: NONE

 

CONNECT 115200

6.3     Transparent + compression V42bis and errors correction

ats95=44

OK

at+CBST=7,0,0

OK

at\N5%C2

OK

atd0556788382

CARRIER 9600

 

PROTOCOL: ALT

 

COMPRESSION: V.42BIS

 

CONNECT 115200

6.4     Transparent + compression MNP5 and errors correction

OK

at&f&wz

OK

ats95=44

ok

at\N5%C1

OK

atd0147282288

CARRIER 9600

 

PROTOCOL: ALT

 

COMPRESSION: CLASS 5

 

CONNECT 115200

6.5     UDI non transparent

ats95=44

OK

at+CBST=71,0,1

OK

atd3611               (this is the French Videotex number (GSM Minitel))

CARRIER 9600

 

PROTOCOL: RLP

 

COMPRESSION: NONE

 

CONNECT 115200

6.6     UDI transparent  (not recommended)

ATS95=44

OK

at+CBST=71,0,0

OK

atd3611

CARRIER 9600

 

PROTOCOL: NONE

 

CONNECT 115200

7.     Fax class

Here's the fax modes supported by our products when used into GSM modes :

 

MC218

MC220, MC222, MC223

GSM Only card

Fax class 1

Supported

Supported

Supported

Fax class 2

Not supported

Supported

Supported

 

We recommend using Fax class 1 (fax process done by the application).

7.1     Note :

When sending fax onto GSM network the PC Cards use the "transparent" mode. This mean the fax quality can be bad (ex: some lines missing), if the GSM network quality is very bad.

8.     Dialling

8.1     Maximum digits

The standard ETSI GSM 04.08 only allow dialling number of 20 digits maximum.

8.2     Pauses / calling tone

- GSM dialling does not support the comma (,) nor any pause when dialling a number.

Note: Most of our firmwares ignore this command.

 

- GSM dialling does not support the "^". Calling tone does not exist for GSM.

Note: Most of our firmwares ignore this command.

 

- In GSM mode you can't dial a voice server then switch to data mode.

Example:

Analog support "ATD0836701313,*,,2,,231,#" (this dial a voice fax server).

But GSM does *not* support this kind of dialling.

9.     COM One company

You can get the update of this document by writing to "support@com1.fr" (mention in the email the version you already have).

Visit our Web site for more information's about our products : http://www.com1.fr