Since the terrorist attacks of September 11, 2001 the federal government has mandated interoperability for police, fire and ems. In other words radios from one agency must be able to talk to radios from another agency.
City of Lubbock public records said, “First responders and emergency personnel could not communicate with each other [during the attacks of September 11], because the different agencies involved used proprietary radio systems which were incompatible.”
The City of Lubbock will upgrade its radios to a set of standards known as P-25. The state of Texas has a P-25 project of its own that theoretically will allow emergency crews to talk to each other even if they are from different cities.