Q: A triple-band phone can be tested in the GSM 900 and GSM 1800 bands but does not find the network in the 1900 MHz band. What's wrong with the tester?
A: There is nothing wrong with the tester but rather with the RF radiation around the phone, or with the phone itself. There are two different possibilities:
a) If there is a menu entry in the mobile phone to select the frequency bands (such as GSM 900, GSM 1800 and GSM 1900), ensure that the band which you want to test is enabled in the phone. Triple-band mobiles with manual frequency band selection include the Siemens S40 and some Motorola phones.
b) If the phone cannot be switched between GSM 900/1800 and GSM 1900, either use a double-shielded RF cable to connect the phone with the tester, or use the Universal Antenna Coupler with the RF Shield Box.
Background: Many triple-band GSM phones scan for networks in the GSM 900 band first, then in the GSM 1800 band. If they find a network there they ignore the GSM 1900 band because most countries offer GSM services either in the 900/1800 MHz bands or in the 800/1900 MHz bands, but not in both combinations. So if your phone is being tested in Europe, Asia or Africa and finds a real network then it will not scan for the test network on the GSM 1900 channels. Keeping the phone in the RF Shield Box is the best way to protect it from radiation from real networks.
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