The comment, from U.K.-based Vodafone chief executive Arun Sarin, comes despite a generally good relationship between the two companies.
Microsoft has made advances with its Windows Mobile OS this year, seeing it included in the Motorola MPx200 on the Orange network as well as the SPV, which is also an Orange "signature phone". However, it faces a tough route ahead against Symbian -- backed by industry giant Nokia, among others -- and even against the Palm OS, now targeted at smart phones almost as much as standalone PDAs.
Sarin said in an interview with the FT: "Hopefully they're working to solve some of the issues that we have and, in time, when they're ready, we'd be very open to talk to them."
A Microsoft spokesman said in response: "Today, Windows Mobile-based smart phones are available from leading mobile operators and leading handset manufacturers in Europe, U.S. and Asia. Microsoft is working with Vodafone on a number of areas, including a mobile Web services standards initiative and we look forward to working with Vodafone to offer Windows Mobile-based smart phones to their customers in the future."
Sarin also spoke widely about the Vodafone brand and how the operator -- the world's largest -- will work with handset suppliers.
His aim is that end users ask for Vodafone devices rather than "a Nokia", to name an obvious example. Japan's NTT DoCoMo, also one of the world's largest cellular operators, has always led on its brand, arguing that when it orders in large volumes, it should be able to decide if a manufacturer gets exposure.
Vodafone, whose reliance on Nokia devices has lessened over the past year, is also in a position to demand more from manufacturers and famously placed an order for two million handsets from Sharp for its Vodafone Live! offering, which was tailor made to its requirements.
Calling brand "a very big issue for us", Sarin said of handset experiences and Vodafone's positioning: "When you turn them on, the picture that comes on is going to be Vodafone. There'll always be one button that you can press and go to Vodafone Live! services. It doesn't matter if you change your phone from a Samsung to a Sharp to a Nokia to Motorola. When the screen comes up it feels like the same experience to the customer."
Since Sarin took over as Vodafone's top executive this summer, commentators have identified a new era in the giant's history, concentrating more on raising average revenue per user -- the crucial ARPU metric -- rather than expanding subscriber numbers or growing by acquisition, which was been a key corporate strategy.
Sarin remains confident the operator, with more than 120 million users in operations in which it is involved worldwide, can grow ARPU, even before 3G technology is rolled out. In October, Sarin predicted Vodafone's 3G effort will kick into gear around next autumn.
Silicon.com's Tony Hallett reported from London.