US mobile payments venture Isis has delayed the launch of its service without setting a new date. The venture between three leading US mobile operators had been expected to debut during September but will not now announce the timing of its launch until October. The service is scheduled to launch in the two US cities of Salt Lake City, Utah, and Austin, Texas. The delay was revealed to Reuters by the venture’s head of marketing, Jaymee Johnson.

Whether the delay has negative consequences for Isis will depend on its rivals. After a slow start, Google changed the model for its wallet service in early August. It is too early to say (and Google has yet to release detailed figures) whether the service has made a step change as a result, although the company did say yesterday that usage of its wallet app has doubled since a new version was launched in early August, without providing further details. Other rivals such as PayPal are still at an early stage.

Perhaps the news this week that Apple is not about to launch a major assault on the mobile-payments market gave Isis pause for thought.

No reason was given for Isis' delay. Johnson said Isis was “wrapping things up and finishing that final punch list of items”, implying only minor issues to contend with. He said Isis’ partnerships for the service had not changed.

Elsewhere, another Isis executive attempted to convey a similar message. Ryan Hughes, the company's chief marketing officer, told GigaOm the delay was not related to major infrastructure changes or a big alteration in strategy but instead that the company was checking the system was right for Isis’ partners and that consumers would be able to use their smartphones for payment straight away.

Isis had billed a summer 2012 launch date, which came to be understood as a September debut, which has now been put back. In fact, this is not its first delay. It had previously said it would launch in the first half of 2012.

However, after its slow start, rival Google is gaining some traction, at least among financial institutions. At the start of August it shifted its business model from one where it negotiated directly with individual card issuers for inclusion in its wallet. Its new model is designed to allow consumers to upload any credit or debit card to the wallet. Card issuers can support a Google Wallet API released in June to make integration easier. Barclaycard US, Green Dot, Silicon Valley Bank as well as six credit unions are among those who have recently signed up, says Google. They join Discover who backed the API in August.