The General Mobile Radio Service (GMRS) is a licensed land-mobile FM UHF radio service in the United States available for short-distance two-way communication. It is intended for use by an adult individual who possesses a valid GMRS license, as well as his or her immediate family members. Immediate relatives of the GMRS system licensee are entitled to communicate among themselves for personal or business purposes, but employees of the licensee, who are not family members, may not use this service.
GMRS radios are typically handheld portable devices much like Family Radio Service (FRS) radios, and share some frequencies with FRS. Mobile and base station-style radios are available as well, but these are normally commercial UHF radios as often used in the public service and commercial land mobile bands. These are legal for use in this service as long as they are GMRS type-approved. They are more expensive than the walkie talkies typically found in discount electronics stores, but are higher quality.
The license extends privileges of the primary licensee to include communications with the licensee's immediate family members, and authorizes immediate family members to use the licensee's station(s) to conduct the activities of the licensee. Additionally, the FCC rules allow GMRS licensees to communicate with other GMRS licensees. GMRS licensees are allowed to communicate with FRS users on those frequencies that are shared between the two services. The rules require each GMRS user family to have a license, rather than (as in the case of commercial and public safety land mobile license) authorizing a licensee's employees to use the same license.
The GMRS-only channels are defined in pairs, with one frequency in the 462 MHz range for simplex and repeater outputs, and another frequency 5 MHz higher for repeater inputs. There are eight channels exclusively for GMRS and seven "interstitial" channels shared with Family Radio Service. GMRS use requires an FCC license, and licensees are permitted to transmit at up to 50 watts on GMRS frequencies (although 1 to 5 watts is more common), as well as have detachable or external antennas.
GMRS licensees are also able to use the first 7 FRS frequencies (the "interstitial" GMRS frequencies), but at the lower 5 watt maximum power output, for a total of 15 channels. FRS channels 8 through 14 are not available for GMRS use; use of these frequencies requires an FRS transceiver.
Recently, hybrid FRS/GMRS consumer radios have been introduced with 22 channels, instead of the 14 channels associated with FRS. On this type of radio, channels 8-14 are strictly license-free FRS channels. Transmitting on all channels above channel 14 requires a license. Transmitting on the shared FRS/GMRS channels 1-7 requires a license, if using more than 1/2 watt. It is the responsibility of the radio user to read and understand all applicable rules and regulations regarding GMRS.
The FCC rules for use of hybrid radios on channels 1-7 require licensing only when operating under the rules that apply to the GMRS. Many hybrid radios have an ERP that is lower than 1/2 watt on channels 1-7, or can be set by the user to operate at low power on these channels. This allows hybrid radios to be used under the license free FRS rules if the ERP is less than 1/2 watt and the unit is certified for FRS operation. Only one maker of hybrid FRS/GMRS radios (Garmin) presently sells radios that will operate on the GMRS repeater channels; the common "22 channel" radios cannot be used with GMRS repeaters.
The requirement for GMRS licensing is ignored by the vast majority of users of these frequencies. Estimates of the number of hybrid FRS/GMRS radios sold to date range from 20 to 50 million units or more. This is compared with approximately 80,000 active GMRS licensees (per the FCC database). Enforcement against individuals is rarely, if ever, attempted. This has led to a lot of consternation among the "non-blister-pack" segment of the GMRS user population, who have significantly more expensive equipment, and have paid $85 for a license. (GMRS and FRS/GMRS radios are often sold in "blister packs" at electronic stores with the required application form for a license included among the warranty cards and safety notices.) Online communities such as GMRS Radio Information and Forums and Popular Wireless Magazines are encouraging GMRS enforcement.
This first set of frequencies shows the split frequency pairs used in duplex operational mode, often used with repeaters. Simplex (same frequency for receiving and transmitting) mode only utilizes the lower set of frequencies.
All channels are used with narrow-band frequency modulation.
|Name||Lower frequency (repeater output) (MHz)||Upper frequency (repeater input) (MHz)||Motorola convention||Icom F21-GM convention||Notes|
|"550"||462.550||467.550||Ch. 15||Ch. 1|
|"575"||462.575||467.575||Ch. 16||Ch. 2|
|"600"||462.600||467.600||Ch. 17||Ch. 3|
|"625"||462.625||467.625||Ch. 18||Ch. 4|
|"650"||462.650||467.650||Ch. 19||Ch. 5||Use not permitted near the Canadian border.|
|"675"||462.675||467.675||Ch. 20||Ch. 6||Suggested nationwide emergency and road information calling. Nationally recognized coded squelch for 675 emergency repeater operation is 141.3 Hz.|
|"700"||462.700||467.700||Ch. 21||Ch. 7||Use not permitted near the Canadian border.|
|"725"||462.725||467.725||Ch. 22||Ch. 8|
This second set of frequencies shows the interstitial ranges shared with the Family Radio Service services. These frequencies can only be used for simplex operations.
|Name||Frequency (MHz)||Motorola convention||Icom F21-GM convention||Notes|
|"5625" or "FRS 1"||462.5625||Ch. 1||Ch. 9|
|"5875" or "FRS 2"||462.5875||Ch. 2||Ch. 10|
|"6125" or "FRS 3"||462.6125||Ch. 3||Ch. 11|
|"6375" or "FRS 4"||462.6375||Ch. 4||Ch. 12|
|"6625" or "FRS 5"||462.6625||Ch. 5||Ch. 13|
|"6875" or "FRS 6"||462.6875||Ch. 6||Ch. 14|
|"7125" or "FRS 7"||462.7125||Ch. 7||Ch. 15|
Note 1: The Personal Radio Steering Group (PRSG) and Popular Wireless Magazines adopted CTCSS 141.3 Hz as the national travel tone for use on all GMRS channels. It is not known how many GMRS licensees have adopted the standard. You can make the travel tone system work by setting one or more of your base-station frequencies to the 141.3 Hz tone.
In the 1960s, the UHF 450-470 MHz band was re-allocated to 25 kHz channels. This meant transmitter deviation was reduced to ±5 kHz. This doubled the number of channels available across the entire 450-470 MHz band. Class B Citizens Radio Service channels were re-allocated to other radio services.
In the 1970s, allowed power was again changed to 50 watts across the output terminals of the transmitter. In the 1980s, licensing of business users was discontinued and businesses were allowed to continue operating until their licenses expired. There was congestion on all channels in larger metropolitan statistical areas and moving businesses to Business Radio Service channels would provide some relief. The radio service was changed to its present name.
In Canada, hand-held GMRS radios up to 2 watts have been approved for use without a license since September 2004. Typically these are dual FRS and GMRS units, with fixed antennas, and operating at 2 watts on some GMRS channels and 0.5 watts on the FRS-only channels. Mobile units (permanently mounted in vehicles), base stations and repeaters are not currently permitted on the GMRS channels in Canada.
Other countries have licensed and unlicensed personal radio services with somewhat similar characteristics, but technical details and operating conditions vary according to national rules. Many European countries use a similar 8 channel system near 446MHz known as PMR446.
The use of GMSR handheld radios is a common method of wireless communication by the Taliban and Al Qaeda in Afganistan. Most notably, the iCom handheld radio, which has recently been adopted by both the Taliban and the US Military for use in squad-level tactical communications.