At present, the retailer has just three flagship outlets, but is planning to open 20 by Christmas, as the start of building a national chain of stores. Competitor Carphone Warehouse will open 100 stores this year.
After a rocky entry to the market in 2003, 3 passed a major milestone in March when the number of its network users in the UK exceeded 3 million. The retailer is a subsidiary of Hong Kong conglomerate Hutchison Whampoa, which also owns Superdrug.
Targets for the additional stores include Bluewater in Kent. Property adviser GVA Grimley is acting as 3's agent.
A 3 spokesman would not confirm store opening plans, but said it is looking at ways to enhance distribution.
At present, 3 sells mobiles through nearly 9,000 outlets, including Carphone Warehouse and Dixons, as well as concessions in Superdrug.
Latest figures from TNS's TeleComTrak show 3 has lost market share over the past 36 weeks to rival networks Orange and Virgin in both contract and pre-pay phones. In the 12 weeks to May 22, its volume share fell from 8 per cent to 7 per cent.
UK shoppers were slow to embrace third-generation (3G) mobile services, such as video messaging, pioneered by 3. However, the public is starting to be won over by access to music video downloads, Big Brother footage and FA Premiership goals.
Last year, 3 grew its customer base from 215,000 to more than 2.5 million in the UK, as customers were seduced by trendy brand advertising and aggressively priced contract packages. It aims to break even before tax, amortisation and depreciation in the second half of this year, with flotation mooted for 2006.
'3 [in the UK] has had a very successful year in 2004,' said the spokesman. 'We are a young brand that is offering something different.'