"We have some fine-tuning issues that have to resolved before we can introduce phones with Smartphone technology," he said. "We have very high-quality standards."
The problem is not Smartphone technology as such, said a T-Mobile representative, but the interplay between the software, hardware and mobile network.
"All three of these components must work together without a glitch before we can introduce a new product to customers," he said. "Our tests so far have shown that this is not the case."
Smartphone software which, like the Pocket PC, is based on Microsoft's Windows CE 3.0 operating system, includes a web browser, e-mail and instant messaging clients, an address book and a media player.
The German mobile operator, which had planned to offer Smartphone-enabled phones by August, now expects to make them available by the end of the year.
Orange's UK arm was the first mobile operator in Europe to launch Microsoft's Smartphone technology, attracting almost 70,000 since its launch last November.
In January, Orange was alerted to a bug in the SPV phone, which Microsoft has fixed with a downloadable patch.