Connecting the modem

The BASIC and PRO versions of IMU come with a GSM modem. The Essentials version does not include a modem and instead, you can use your own mobile phone with this version. Note that within the U.S., Cingular/AT&T, T-Mobile and US Cellular use GSM.

Preparing the modem

There is a little bit of preparation involved before a modem is active on a cellular network.

GSM modems

With GSM modems, you must insert a SIM card into the slot on the front of the modem. This must be a valid SIM card with an active service plan that allows for receiving and sending of SMS messages.

• For occasional use, if you have a SIM card already in your phone, you can simply take it out and put it in the modem.
• For full-time use, go to a retail store of a GSM provider (example: Cingular/AT&T, T-Mobile, US Cellular) and ask for a SIM that is provisioned for SMS. "Provisioned" is tech-talk for buying a plan that includes SMS -- choose a plan with maximum text messages.
       Note: As of late 2004, the "Blackberry" plan from T-Mobile is an excellent choice. For around $50/month, you get unlimited incoming and outgoing text messages. Plus, T-Mobile appears to have excellent coverage in the U.S.
       Since the same SIM card will work in mobile phones, you may want to check the SIM card before putting it into the modem. Insert the SIM into your GSM-enabled mobile phone and make sure that you can send and receive messages. This is also a good time to write down the exact phone number (this is called the Subscriber Number) that corresponds with the SIM, because you will need this during the IMU setup procedure.

After you have placed a SIM into the modem and verified the subscriber number for the device, attach an antenna and power supply to the modem.

Using your own phone

IMU allows you to use your own phone as a modem, as long as your phone is ETSI compliant and "provisioned" or activated to send and receive text messages.

As with the GSM modem, you must have an active service plan that allows for the sending and receiving of text messages. In many cases, you can get a "data only" plan. This is of course, very cost effective.

Connecting the modem or phone to a PC

Once the modem or phone has been prepared for use, connect it to a serial port or USB port on your PC using the data cable that is included with the modem, or using a data cable that is compatible with your phone.

Once the modem or phone has been connected to a PC, you may apply power to the modem.

Modem lights

Once the modem has been prepared and connected to a PC, you should see one or more lights on the modem:

• For GSM modems with one light, you should see this light come on steady, and then start flashing after a minute.

• For GSM modems with multiple lights, you should see the LS light come on steady, and then start flashing after a minute.

• When using your own phone, it may or may not have a light which periodically flashes, or it may have a signal indicator that shows you a number of "bars" to indicate the signal strength.

The flashing light on a GSM modem indicates that the modem is receiving power and that it is communicating with the mobile network. If the light is not on, it may mean that the modem is not receiving power. If the light is not flashing, this means that the modem is not able to communicate with the mobile network. This may be because of an invalid SIM, or because of very weak signal. This should be corrected before proceeding.