1. 1
Software Testing Environment:
Operating System: Windows 7
HyperTerminal Private Edition 6.3
Virtual Operating System: Debian‐Linux OS with VMware Player User Interface
Additional Perl script files for Network connection:
tmobile.dat, att.dat, tmobile_chatscripts.dat, att_chatscripts.dat, options.dat
Testing Procedure:
Phase 1 Initial PC to Modem communication test
Purpose: Confirm modem recognition on Windows 7 OS
Confirm Sim900 module responds to basic AT commands
Step 1: Ensure a working SIM card is correctly placed in the SIM receptacle.
The SIM card must have SMS, Data,Voice and web browsing capa‐
bility for the modem to function properly.
Step 2: Attach the modem to the PC USB port using the USB cable provided
for testing. It is recommended that you have an internet connection
Established to ensure the latest generic modem and serial port
drivers are installed. Wait for the installation to complete and verify
the message “your device is ready to use” is displayed. At this point
you may terminate your internet connection.
Step 3: In Windows, run the HyperTerminal Program. You will be prompted
to set up and name a new connection. Type any name for this
connection and press ok.

2. 2
You now will be prompted to configure this connection:
Verify your port setting(COM#) for the modem is correct and set the
port setting parameters as shown above and press ok. Make sure
CapsLk is enabled and in the HyperTerminal screen type, AT then
press Enter.

3. 3
The response OK verifies the modem has established communication
with Windows via HyperTerminal. Next type AT+CGMM and press
Enter. The response should be SIMCOM_SIM900 verifying the SIM
module is functioning properly. Now test for SMS functionality by
typing AT+CGMS=”##########”, this can be any 10 digit number that
has SMS capability. In this case, I entered my cell number. Press Enter
and you will be prompted to type your message. Press Ctrl+Z to send
and your message should arrive at its destination number. This
verifies SMS functionality.
This completes the first Phase of testing and ensures the modem is
functioning properly on a basic communications level.

4. 4
Testing Procedure: Continued
Phase 2 Connectivity test
Purpose: Establish GPRS connection on T‐Mobile and AT&T Networks using
Debian‐linux OS with VMware Player user interface. Test web
browsing functionality and monitor Network statistics to ensure
modem connection is stable and operating within acceptable
standards.
Step 1: Close Windows HyperTerminal. Run the VMware Player. At this point
your modem is still connected to the host OS‐Windows. If the VM‐
ware Player is not in full screen mode(recommended) you will no‐
tice as greyed out USB device icon in the bottom right corner. This
indicates the modem is not yet connected to the VMware Player.
Left click this Icon with your mouse to open the pop up menu and
select connect(disconnect from host). This will disconnect the mod‐
em from Windows and connect it to the VMware Player/Linux OS.
Step 2: In the VMware Player desktop, click the root terminal icon(red) and
at the prompt type “tail –f /var/log/syslog” without the quotes and
press enter. This terminal will serve as a real‐time process monitor of
exactly what is happening during the connection process, so if there
is a problem during connecting you can pinpoint at what point the
connection process failed. Open another root terminal window and
place such that both windows can be viewed simultaneously. Now, in
the new terminal you have opened, type “cd /etc/ppp/peers”
without the quotes and press enter. This is where the connection
scripts are stored. Ensure your modem, or more importantly the
antenna is not placed near power sources and at least 8 inches from
the human body as this may affect the connection process. At the
prompt type, “pppd call tmobile” without the quotes and press
enter. This will execute the tmobile connect script. You may watch
the connection process in the other terminal. The process takes
approximately 5‐10 seconds and in the process monitoring terminal
you will see the line similar to “Aug 7 14:55:13 kalman‐vm‐debian
pppd[3190] Script /etc/ppp/ip‐up finished (pid 3196), status 0x0”
which indicates that you have successfully established the T‐mobile
connection.

5. 5
Step 3: Now we will use Ping, a network utility built into the VMware Player
to monitor network performance, which include ping times and
packet loss information. In the VMware Player click the
“Applications” tab in the upper left corner. In the drop down menu
select System Tools> Network Tools. Under the devices tab verify the
modem is selected. Now select the Ping tab. You will be prompted to
enter an ip address to ping and the number of times you wish to ping
the address. You may select Unlimited although in reality the process
stops after 5000 ping requests but your connection will still remain
established. Press the Ping button and you will see graphical bar
graphs representing ping times in milliseconds. In addition,
diagnostic information showing the min, max and mean ping times
along with successful packet transmission information. In general a
2% packet loss is acceptable but it is not uncommon to notice a 5‐
10% packet loss for gprs modems. The causes of packet loss may be
due to a number of issues, including network congestion,
interference with the antenna or issues with the mobile service. If an
un‐acceptable packet loss in noticed during this test, it Is advised to
terminate the connection and go back to Windows HyperTerminal to
test the signal strength. This can be done by typing “AT+CSQ”
without quotes in the HyperTerminal. A value from 10‐31 is
acceptable. A lower value should require further board inspection to
ensure there are no defects on the printed circuit board.
To test web browsing capability you may open VMware’s built in
browser to verify web browsing is functional. Please be aware that
the SIM900 module has a max 85.6 kb/s downlink and attempting to
stream HD audio/video beyond its capability may lead to undesired
performance and or connection problems.

6. 6
As shown above is a screenshot taken during testing of Pixel Sand’s
USB GPRS modem which indicates 98% successful packets
transmitted over a 533 packet transmission period.
Step 4: Testing over AT&T networks will follow the exact same procedure
demonstrated in steps 1‐3. Before proceeding please disconnect the
modem from the VMware Player by clicking the USB device Icon and
select “disconnect” connect to host. Now safely remove the USB
modem from the USB port and replace the T‐mobile SIM card with an
AT&T SIM card. Follow the same procedures with the exception in
Step 2, instead of typing pppd call tmobile, type instead pppd call att.
This concludes Pixel Sand’s USB GPRS testing procedure.