GPS RADIO COMBOS
Another twist on the FRS-type units are the Rino units offered by Garmin. These combine an FRS radio with a GPS receiver, all packed in a small handheld unit. There are several models available, including ones with color displays and the ability to store maps and a large number of recorded coordinates. An added benefit to these radios is the ability to display on the screen the location of others in your group using another Rino radio/GPS unit.
The Rino is a handy unit to have, even when riding an ATV, motorcycle, or snowmobile as it can be used for communication, tracking of your fellow riders, and for navigation purposes. Models are available with both FRS and GMRS frequency capability.
Ham radio gear is available...
Ham radio gear is available in walkie-talkies and as higher-power mobile units. These can offer you the best range and clarity of all the communication options. However, the cost is generally higher, and you and others you're talking to will need to have the appropriate FCC license.
Beyond the more commonly used public radio systems described above, there are also available communications using ham radio frequencies. Licensing is required, but the possibilities of using portable, mobile, and base station setups opens up numerous possibilities with options to improve antenna configuration and power outputs.
With these setups you can configure systems that can communicate over the longest distances due to the allowed transmit powers. These are typically the highest-cost radios as well. Additionally, with access to repeater stations, a person may be able to communicate over hundreds of miles and possibly make use of a remote phone line with the help of ham club systems.
It is possible in some cases to use a cell phone for communication on the trail, but you're highly limited by proximity to a local cell site. Once you get in remote areas, the usefulness of a cell phone drops tremendously. Also, cell phones are not conducive for group communications.
With exception to a ham radio, a cell phone is probably your best bet when it comes to trying to contact emergency services, with limitation based on access to a cell tower signal.