Each baby monitor has an operating frequency band listed on its packaging -- typically either 900 MHz or 2.4 GHz. Take an inventory of the electronics in your home and find out which frequencies they use, so you can choose a baby monitor that operates on a different frequency band and won't interfere with devices such as a wireless router or cordless phone. Interference can range from a bad signal to a virtually inoperable phone or computer, so it's important to find a monitor that coexists peacefully with your other electronics.
Some digital monitors now use the 1.9 GHz frequency band, which sees less traffic and can help minimize interference. Models that offer this baby monitor frequency band use digital enhanced cordless telecommunications technology. A DECT monitor may be the best option when it comes to frequency but is usually more expensive.
If you're unsure which frequency you need or can't find an affordable monitor with a unique frequency, you can always buy what you think is the best baby monitor for you and see how it works in your home. Many parents who worry about interference experience few problems with it, largely due to the location of their electronics in relation to the baby monitor.
You may also be able to mitigate any issues by selecting a baby monitor with multiple channels. To help minimize interference from nearby electronic devices, many inexpensive baby monitors offer a range of channels within their particular frequency band (similar to AM or FM radio). That means even if multiple devices in your home share the same frequency band, changing the channel can eliminate interference. Baby monitors can have as few as two or as many as 60 available channels.