PORTLAND, Maine — While the existing city communications system is still “solid,” according to Police Chief Michael Sauschuck, the time has come for something new.

“We know we have a system that has reached its end of life,” Sauschuck said Monday about the network that handles more than 66,000 emergency calls annually and communications between city departments.

Sauschuck said the system is still up to meeting demands.

“The system we have now is operational, we are just more concerned with support from the vendor and parts for the system,” he said.

Interested vendors have until March 24 to respond to a request for proposals to replace the hardware and software in the 10-channel system that was installed in 1999.

The estimated replacement cost is $9 million, with the city planning to borrow $7 million in next year’s capital improvements budget.

The $7 million is almost 50 percent of next year’s $14.25 million bonding plan for municipal and school infrastructure projects, improvements and vehicles.

Acting City Manager Sheila Hill-Christian said earlier this month that 30 percent of the total cost will be paid by South Portland, which shares dispatching services.

The dispatch center at police headquarters at 109 Middle St. has been handling calls for Cape Elizabeth for almost a decade and for South Portland since 2011.

South Portland City Manager Jim Gailey on Monday said no decisions have been made in his city about how to help pay for the new system.

“This price tag is still a number in the works and how it is split between South Portland and Portland is still in discussion,” Gailey said in an email.

The linchpin of the communications system is emergency response, and Sauschuck said there are 37 dispatchers handling calls for Portland, South Portland and Cape Elizabeth.

Thirty-one of the dispatchers are Portland city employees, and eventually all will be as positions now filled by South Portland employees become vacant, Sauschuck said.

On Monday, Cape Elizabeth Town Manager Mike McGovern said the town pays $167,500 annually for dispatch services. Sauschuck said Cape Elizabeth will not be contributing to the cost of a new system.

The 122-page RFP details the need for a complete system, from consoles to software to replacements for 1,300 portable and base radios. The city is seeking one vendor to provide the whole package in a fully digital system.

“It was a great system when it went in. But like everything else, changes happen,” Sauschuck said.

System software platforms are outdated and will no longer be supported. Some radio and hardware parts are no longer manufactured and will soon be unavailable from suppliers, the chief said.

The replacement could require new towers or hardware on towers to ensure total access to the system, but a 2013 report from Barrington, New Hampshire-based Communications Design Consulting Group said the current set-up of 10 radio channels broadcasting at 800 megahertz is sufficient.

The report said hand-held radio communication “remains the top concern for most users interviewed,” but added nearly 1,200 of the radios in use can be reprogrammed to work with a new communications system. There are more than 230 radios in need of full replacement, according to the report.

The communications system is also required by federal regulations to connect to municipal departments for daily operations and in case of emergencies. A new system would allow for texting in addition to voice transmissions.