Competition for mobile phone vendors spiked Friday as Japan's three top players began taking pre-orders for Apple Inc.'s iPhone 5C. The recent decision by NTT DoCoMo Inc. to finally sell iPhones now puts more pressure on rivals KDDI and Softbank.

Sales of the latest iPhone models — the 5C and more upmarket 5S — begin Friday.

In an apparent bid to halt the erosion of its customer base, market leader DoCoMo said it is essentially giving away the 16GB and 32GB versions of the cheaper model, the brightly colored iPhone 5C, to anybody — even current customers — who signs a two-year contract.

Although the actual handset prices of the two models are ¥85,680 and ¥95,760, depending on memory size, people can effectively get them for free through monthly discounts that over the two years equal the handsets' prices.

The same deal applies to the high-end 16GB iPhone 5S, DoCoMo said. The 32GB model will cost ¥10,080 and the 64GB ¥20,160.

No pre-orders are being taken for the iPhone 5S.

Depending on whether subscribers are new or current, KDDI Corp., which runs the au brand, is offering the 16GB iPhone 5Cs for either ¥0 or for ¥3,240 with a two-year contract. The 32GB model will go for either ¥4,800 or ¥14,160 with the contract.

KDDI's actual handset prices for the iPhone 5C are ¥52,920 for the 16GB model and ¥63,000 for the 32GB.

Softbank said the iPhone 5C 16GB model will essentially be free to new subscribers and ¥135 for existing users with a two-year contract, while the 32GB version will cost ¥200 or ¥590, respectively.

The actual handset prices are ¥52,920 for the 16GB version and ¥63,000 for the 32GB version.

KDDI, DoCoMo and Softbank Corp. say their monthly data network fee is ¥5,460.