Republic Wireless customers could experience some dropped calls or poor quality in the next few weeks – if they’re using Sprint’s cellular network.

Raleigh-based Republic announced that upgrades to Sprint’s network in the Raleigh-Durham area could disrupt some calls on the network. But the majority of Republic calls are carried on wi-fi networks. Republic offers a hybrid service that operates primarily on wi-fi but switches to Sprint’s cellular when wi-fi is not available. The service launched in 2012. In November, Republic launched a new phone and a wider range of service plans that start at $5 a month.

Sprint has been rolling out its “Sprint Spark” network upgrades to deliver faster speeds at up to 2 gigabits per second – faster than the 4G speeds offered by larger rivals AT&T and Verizon. Republic said that the Sprint upgrade started last week and will continue through early January.