Rivalry among Hong Kong's mobile networks continues to heat up with Hutchison and Sunday yesterday making new moves to attract and retain customers who may be tempted to switch providers at the end of this month. March 1 marks the start of mobile-number portability (MNP), which allows cellular users to change service providers yet retain their personal phone number. Hutchison said it would match any service plan offered by any network in the SAR. 'Customers can choose from the most favourable basic monthly plans from the 40 or more different ones offered by Hong Kong network operators,' it said. Sunday, which is a PCS network operator, launched a high-profile advertising campaign aimed at educating customers of the change in the market. It hopes to be a significant beneficiary as people swap networks more freely. Research carried out on behalf of Sunday showed 49 per cent of people would be interested in moving, managing director Craig Ehrlich said. Sunday chairman Richard Siemens said MNP would mean all the networks being placed on an equal footing as customers moved to get better prices and service. 'By the end of this year all of Hong Kong's providers will have more or less 500,000 customers each,' he said. During December it had signed up 20,000 new subscribers, reaching 'more than 200,000 customers'. However he saw the market growing by only about 10 per cent this year, meaning that most new customers would be switching from other networks. An average 3 per cent to 3.2 per cent of people left Sunday each month last year, Mr Ehrlich said. He expected that to rise to as high as 4 per cent this year due to MNP. 'As the networks become equal the bottom line will be customer service and branding,' he said.