As the Baltimore comptroller's office was seeking bids for a multimillion-dollar upgrade of the city government's telephone system last year, the mayor's technology office was buying about $500,000 worth of equipment that could be used for the same kind of system upgrade, documents show.

The mayor's office says the purchases were part of a pilot project and that only about $55,000 was spent on equipment for the new Voice over Internet Protocol (VoIP) system. The additional money was spent on equipment that was used for other computer-related needs, a spokesman for the mayor said.

But a purchase order from the Mayor's Office of Information Technology shows it spent $441,450 on switches that would provide the "VoIP switch infrastructure for buildings in the downtown Baltimore campus." And phone technology experts say the 124 computer switches included more expensive features primarily used for phones.

The dueling attempts to upgrade City Hall's aging telephone system have pitted two of the city's elected Democratic powerhouses — Comptroller Joan M. Pratt and Mayor Stephanie Rawlings-Blake — against one another, while stoking debate over how to best spend taxpayer money.

The mayor says her technology office is best equipped to oversee the complicated new computer-based phone system, while the comptroller says the mayor is circumventing the government procurement process by purchasing the equipment through a 2010 contract rather than engaging in a new round of competitive bidding. Pratt called that "illegal."

The battle could heat up Wednesday when the city's spending board, of which Pratt and Rawlings-Blake are members, takes up the issue.

Pratt's office wants to award a $7.4 million contract to overhaul the phone system to IBM, the winner of its lengthy competitive bidding process. The mayor's office has declined to say how she and her two appointees to the five-member board will vote, though a spokesman says Rawlings-Blake has questions about the deal.

The turf war became public when the comptroller accused the technology office of trying to circumvent the competitive bidding process by cobbling a phone system together under an existing contract. Pratt has accused Rawlings-Blake of telling "an untruth" about her knowledge of the purchases.

Rawlings-Blake has vehemently disputed Pratt's claims and demanded an apology. The mayor and her aides staunchly defend the purchases and say that buying what they characterize as small amounts of phone equipment did not violate purchasing rules.

Baltimore political observer Matthew Crenson said the failure of the comptroller's and mayor's office to work together on this issue shows a dysfunction in City Hall that should be troubling to taxpayers.

"It sounds as if the mayor's office hasn't been talking to the comptroller's office," said Crenson, professor emeritus of political science at the Johns Hopkins University. "If they had been, they could have settled this whole thing much more quietly."

At issue is who should upgrade the city's outdated phone system. Most workplaces have converted to a VoIP system that allows employees to get voice mail via email and is more cost-effective because fewer phones lines are needed.

The city's budget — drafted by Rawlings-Blake's finance office and approved by the Board of Estimates — noted for both the current and past fiscal year that Pratt's office would lead a competitive process to install a new phone system.

The mayor's technology office purchased Cisco equipment — the 124 switches, 80 VoIP phones, including some with video touch screens, and other items — on May 23 and June 13, 2011, city records show. The June purchase order listed other equipment that would be needed to complete the transition to a VoIP system, including "a small number of additional switches."

Meanwhile, bids for the phone project were due to Pratt's office on May 25, 2011.

The simultaneous efforts took place in City Hall buildings a block apart. While Pratt sought input from officials in Rawlings-Blake's technology office, she said they didn't give her the same courtesy and never informed her of their equipment purchases.

Ryan O'Doherty, a mayoral spokesman, said Rawlings-Blake believes the technology office has the knowledge and expertise to best implement a new phone system, not the comptroller's office. He and outside VoIP experts said that the new high-tech phones are usually overseen by technology workers, not phone officials. This type of phone system hooks into an existing data network.

"We've been very clear from the beginning that our technology office thought there was a pretty good chance for the city to implement this project with less outsourcing, in a faster time and with less costs," O'Doherty said.

The mayor's former chief technology officer, Rico Singleton, did approach Pratt in December — months after companies had turned in competitive bids for the phone system project — and proposed taking charge of the phone system overhaul using Cisco equipment to switch to VoIP.

After conferring with consultants, Pratt rejected the idea. O'Doherty described Singleton's plan as not a "formal proposal."