Linfox Armaguard is the company in talks to launch a takeover bid for Customers Limited, the largest operator of automatic teller machines in Australia.Media speculation about an offer for the ASX-listed Customers first surfaced in May. Speculation then was that the offer came from a private equity firm. The company told the ASX three weeks ago that it had "held discussions with a potential purchaser", after the ASX queried a rise in the share price.Neither Linfox nor Customers would comment on inquiries yesterday. It is not clear whether they are likely to reach terms.Shares in Customers have softened since the ASX queried the company on 17 October. The shares closed yesterday at A$1.03, down from a fleeting peak of $1.22 on the day of the inquiry.Operators of armoured cars such as Armaguard are under earnings pressure thanks to the shared sourcing arrangements of banks, and efforts by banks to cap cost growth from suppliers.The four major banks all source cash distribution through Cash Services Australia, a joint venture formed by ANZ, Commonwealth and Westpac in 2001. National Australia Bank joined CSA in 2006.Research by IBISWorld puts the annual revenue of Linfox Proprietary, including Armaguard, at around A$300 million, though it's not clear how much of this relates to cash distribution.If Customers Limited does change hands it will be the fourth time since the founding of the business - originally known as ATM Solutions - in the late 1990s.Bank of Queensland then Macquarie Bank both bought the firm. It was then sold on after only a few years. What is now Customers (then a micro cap under different management) bought the business in 2007.Customers operates around 5700 ATMs in Australia, accounting for around one-quarter of the market as measured by ATM numbers.