In the early 1890's call boxes were installed for "beat officers" to communicate with headquarters. As the population of Denver grew and technology advanced, other means of communication were needed. In 1932 ten police cars were outfitted with AM radios. In 1939 the Denver Police Transmitter was moved to 9th and Columbine from 21st and Lawrence where they were called Denver Police Radio Service. In the early 1940's after the new police building at 13th and Champa was occupied the Denver Police Radio Room was hailed as a modern day police communication center.

There was no 911 system. There were only two telephone numbers to the Police Department. One number went directly to the dispatch center and was considered the emergency number. The other was answered at the switchboard. The switchboard was the old style PBX board. It consisted of a number of cables representing the incoming phone lines. Each incoming line was one of a pair. Incoming calls were answered by one of two operators who picked up a cable and plugged it into the appropriate port on the board. The operator determined the nature of the call, plugged the companion cable into the proper extension port and closed a toggle switch that caused a phone at the proper location to ring. Two civilian operators attended the switchboard during the day and were relieved by Police officers at night and early morning. In addition to taking incoming calls, these operators also received and logged "pulls" from the many beat officers throughout the city

Since at least 1937, KAA 59, a CW station used for national wants and warrants clearances. This station was operated by Radio Engineers. Operation of this station was in fact the primary duty of the Radio Engineers with radio maintenance being secondary. The last contact was made in 1968 by R.E. Larry Fenstemaker. This was the predecessor to LETSMUS and NCIC which is now available to the cars through the MCT system.

Denver Police radio was a one frequency operation in the 40's and 50's. There were no portable radios, and no multi-channel dispatching. All users of the Denver Police radio system were on the same channel, which was one way, being received at the cars by the stock AM radio. The call letters were KGPX at 1610 kilocycles. In addition to dispatching for Denver Police we also dispatched for a number of surrounding jurisdictions. At night when weather conditions were favorable, we functioned as a relay station to several cities in the western half of the United States. It was not unusual for a District 3 car to be sent to Ruby Hill to copy a radio transmission from Indio, CA to be relayed to Kansas. On occasion the Grand Junction Police dispatch came in so loud and clear that Denver officers responded to radio communications that were intended for officers on the western slope.

In the early 50's the dispatch frequency was changed to the FM band and the call sign became KAA-511. This move accomplished several things. Two way radio was implemented between the cars and the dispatcher from the fixed mobile radio in the patrol cars. It improved the reception on the street, eliminated most of the dead spots, eliminated the long range and skip problems of the AM frequencies and made Denver less involved in out of city and out of state radio traffic. The FM change was also the precursor to the multi channel operation. In 1956 Denver became the first city to use a repeater system.

While the dispatch center was on the first floor of the Police Building at 13th and Champa, the Transmitter and Police Radio Repair Shop was at 9th and Columbine. At that time the Police and Fire Departments maintained separate dispatch and repair facilities. Denver Police Radio Engineers were really pioneers in Police Radio Communication. They were the designers of the system and leaders in such things as standardizing radio receivers so that a bad order radio could be replaced in a matter of minutes. This avoided the problem of cars being out of service for extended periods of time. Early in the 50's the Radio Engineers, especially John Thomas recognized the value of having the transmitter located on a mountain. After many years of planning and hard work this was eventually accomplished. Unfortunately, John Thomas retired before he could see his dream come true.

In The late 1960’s Denver Police was using a two channel VHF radio system with fixed mobile radios in the patrol cars. Under Bob Danhour, The Superintendent of Radio Engineers, the radio site was moved to a mountaintop overlooking Denver. A third and fourth channel were eventually added. A new dispatch center with four positions supporting four channels was implemented and designed and built by the Radio Engineers located at the Police Building at 13th and Champa. This arrangement made Denver the first Police Department capable of simulcast on all channels. The name was changed from the Transmitter to the Electronic Engineering Bureau.

In the early 1970’s portable radios were added to the radio system, the cars being equipped with vehicular charger units that make the portable act like a mobile radio while in the vehicle. In 1970 Denver started "911" service to the city switchboard. In 1976 With the advent of the new Police Headquarters building at 13th and Cherokee five new Motorola dispatch consoles supporting a main and backup position each were implemented on the VHF radio system. In 1978 a UHF Motorola system was implemented using MT500 portable radios and vehicular charger units on an 8 channel conventional radio system. In 1977 Denver Police attempted to use a home written CAD (Computer Aided Dispatch) system that did not work as expected. This was supposed to replace the card conveyer system. In 1983 the Police Department took over 911 operations. From 1989 until 1991 an AT&T CAD system was implemented that did not work. In 1993 the PSSI CAD system that we are currently using was activated. It is a solid, stable system that serves us well.

In 1978 the Electronic Engineering Bureau was civilianized. As the Radio Engineers left or retired they were replaced by civilian technicians.  In January 2003 Bob Lindner, the last Radio Engineer retired leaving the bureau totally civilianized. In May 2002 Larry Fenstemaker, the last Superintendent of Radio Engineers retired. He was replaced by Dana Hansen, the first civilian commander of the bureau. Dana served in this position until 2007 when she moved on to private industry.  Dana was instrumental in making Denver a leader in interoperable communications, allowing Denver for the first time to communicate with neighboring jurisdictions.  Dana also led the EEB away from the Police Department and into Technology Services for the City of Denver.  Dana was replaced by Gary Pasicznyk, formerly the supervisor of the infrastructure maintenance section of the EEB.