Question:
I read that IMU directly supports both GSM and CDMA modems. Which type of modem is best for me? |
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Answer:
It is true that IMU supports both GSM and CDMA modems, but there are a few things to keep in mind.
1. Unlike GSM modems and phones, which all use a uniform set of commands set forth by the ETSI standard, CDMA modems don't have the same level of uniformity. Because of this, IMU supports only one brand of CDMA modem -- one made by the company AnyDATA. This means that other types of CDMA modems such as the "Aircard" made by Sierra Wireless will not work with IMU.
2. There is an operational undesirability with respect to CDMA in the U.S.A. If someone who has a GSM phone sends IMU a message on a phone number that is being serviced by the CDMA modem, IMU will receive the message text itself, but IMU will not receive the phone number. This means that you will not really know precisely "who" sent the message and because of this, you will not be able to reply to that person.
3. Generally it only makes sense to use CDMA modems in countries that do not have good "interoperability". For example, there are countries in Latin America that have both CDMA and GSM carriers (just like the U.S.A). However, unlike the U.S.A., if a person with a CDMA phone sends a text message to their buddy who has a GSM phone, the GSM phone will not receive the message, and vice-versa. This is because the mobile carriers (falsely) believe that they will make more money by keeping the text messaging only within their own carrier and thus, try to discourage competition. This has been tried all over the world, and slowly, country-by-country, the mobile carriers discover that they make the most money by allowing messages to flow freely between the carriers. In any event, in these Latin American countries, IMU may be used with two modems simultaneously -- one GSM and one CDMA -- so that all messages will be received by customers no matter who their mobile carrier is.
Since the U.S.A. has very good interoperability between carriers, and since you can always receive both the message text and phone number if you use a GSM modem, we strongly suggest that only GSM modems be used in the U.S.A. |
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