DSL Tips and Tricks :: How to make a BT - mobile phone GPRS connection

This is part 4 of the DSL Bluetooth how-to. In order to proceed from here, you will need to have Bluetooth up and running on your DSL machine and be able to "pair" with a Bluetooth mobile phone as described in part 1 - "How to start Bluetooth & Pair with a remote device". You will also need to know how to discover which sdp channel your phone uses for dialup networking and bind this to a Bluetooth com port as described in part 2 - "How to dialup using a mobile phone via Bluetooth".

This might seem obvious, but you need to have GPRS enabled by your telecomms provider for your mobile phone and you will need to know if any special parameters are required to establish the connection. I believe most providers rely on your phone's SIM card for identification, so no addtional login or password is typically required.

I have not been able to make wvdial work with GPRS - it looks like it's working, data comes and goes from the phone but does not make it back to DSL. The problem might be that "apt-get install wvdial" over-writes the symlink from /etc/ppp to /opt/ppp in DSL, but anyway, after much Googling I found a different solution (mostly from http://home.comcast.net/~spearcd/gprsdun.html). Note I have little idea what several of these settings do - if anybody would like to suggest corrections, please feel free.

First we need to create 3 files, as root, in /opt/ppp/peers:

# File name: gprs-connect-chat
#
'' AT
# Replace "mnet" with the name of your GPRS service
OK AT+CGDCONT=1,"IP","mnet"
# This tells the phone to use the GPRS entry created above
OK ATD*99***1#
# If you have only one entry *99# will probably work.
CONNECT ''
# EOF

# File gprs-disconnect-chat
#
# This is called at <ctrl-c>, I have little idea what it does
exec /usr/sbin/chat -V -s -S                             \
ABORT                  "BUSY"                 \
ABORT                  "ERROR"                               \
ABORT                  "NO DIALTONE"                \
SAY                        "n\Sending break to the modem\n"                  \
""                            "\K"                                        \
""                            "\K"                                        \
""                            "\K"                                        \
""                            "+++ATH"                            \
""                            "+++ATH"                            \
""                            "+++ATH"                            \
SAY                "\nPDP context detached\n"
# EOF

# Filename: gprs
#
# Most GPRS-enabled wireless devices don't reply to LCP echo's
lcp-echo-failure 0
lcp-echo-interval 0
nodetach
# Connect script:
connect "/usr/sbin/chat -v -t3 -f /etc/ppp/peers/gprs-connect-chat"
# Disconnect script:
disconnect /etc/ppp/peers/gprs-disconnect-chat
# Connection method used to wireless device:
/dev/rfcomm0
115200    # Fast enough for GPRS and EDGE handsets.
# Hardware flow control:
crtscts
# Ignore carrier detect signal from the modem:
local
# IP addresses, etc:
:10.0.0.1
noipdefault
ipcp-accept-local
defaultroute
usepeerdns
# specifically addressed to the serial connection, not the GPRS connection)
novj
nobsdcomp
novjccomp
nopcomp
noaccomp
# This disables authentication
user "username"
persist
maxfail 99
# EOF

Once these files are saved (and added to .filetool.lst), we can get started:

# hcitool scan
Scanning ...
       00:0A:D9:E8:4A:65       .P900
# hcitool cc 00:0A:D9:E8:4A:65
# hcitool auth 00:0A:D9:E8:4A:65
# rfcomm bind 0 00:0A:D9:E8:4A:65 7
# mknod -m 666 /dev/rfcomm0 c 216 0
# sdpd
# sdptool add --channel=7 DUN
Dial-Up Networking service registered

Then all that remains is to dial. Although there are several error messages, it works:

# /usr/sbin/pppd call gprs
Serial connection established.
Using interface ppp0
Connect: ppp0 <--> /dev/rfcomm0
Cannot determine ethernet address for proxy ARP
local  IP address 217.164.89.221
remote IP address 10.0.0.1
primary   DNS address 195.229.241.222
secondary DNS address 213.42.20.20

The first terminal window will remain blocked whilst the connection is made so open a second terminal window to test the connection:

# ping damnsmalllinux.org
PING damnsmalllinux.org (65.254.46.177): 56 data bytes
64 bytes from 65.254.46.177: icmp_seq=0 ttl=49 time=1128.3 ms
64 bytes from 65.254.46.177: icmp_seq=1 ttl=49 time=1042.2 ms
64 bytes from 65.254.46.177: icmp_seq=2 ttl=49 time=902.9 ms
<ctrl-c>
--- damnsmalllinux.org ping statistics ---
4 packets transmitted, 3 packets received, 25% packet loss
round-trip min/avg/max = 902.9/1024.4/1128.3 ms

Return to the first terminal window to close the connection:

<ctrl-c>
Terminating on signal 2.
Connection terminated.
Connect time 7.3 minutes.
Sent 21380 bytes, received 248664 bytes.
sh: line 1: /etc/ppp/peers/gprs-disconnect-chat: Permission denied
disconnect script failed

I tried http://promos.mcafee.com/speedometer/test_0150.asp with Firefox which rated the connection at 45Kbit/s - this would certainly depend on the strength of the telecomms network signal but it also depends on how far the phone is from your DSL machine. Mine will still connect when the phone is 6-7 metres away but it is much slower.

When I first started with DSL, I would never have believed Bluetooth would work, let alone a GPRS connection, which shows the power of this software - I didn't see my phone bill yet though