Why have 900 MHz ISM WLANs lost favor compared to 2.4 GHz and 5 GHz?

• A. They have the same cost as 2.4/5 GHz.
• B. They offer the same throughput as 2.4/5 GHz.
• C. They are more expensive and provide slower data throughput.
• D. They require licensing.

Answer: (C)

The main idea here is that throughput and cost drive whether a wireless band stays popular. The 900 MHz ISM band can push signals farther and through walls better than higher frequencies, but it can’t deliver the same data speeds because there’s less spectrum available and the radios/modulation used in that band are less capable of high-throughput data. In practice, the channel bandwidth at 900 MHz is narrow and the modulation schemes are older, so the maximum speeds are much lower than what modern 2.4 GHz and especially 5 GHz Wi‑Fi can achieve.

At the same time, the market and manufacturing focus shifted toward 2.4 GHz and 5 GHz because they offer much more spectrum, more channels, and support for the latest high-speed standards. That combination lowers hardware costs and increases performance and ecosystem availability. Licensing isn’t the limiting factor for these ISM bands, so the big pull toward the other bands is the speed and cost advantages, not licensing, which helps explain why 900 MHz WLANs fell out of favor.