Experts are saying that Google's new Internet-calling service must add more mobile capabilities and support for business customers to compete with Skype and rival Web-phone providers.

Gmail, the world's third-largest e-mail site that boasts of 186 million users, introduced the feature this week. In a blog post, the company said that the service allows users make voice calls to a wireless or landline phone using a computer. The feature will be available free of charge when making calls within the U.S. and Canada. Phone calls made from other territories have prices that range from 2 cents to $4.99 a minute.

In an interview with Bloomberg, Jayanth Angl, an analyst at Info-Tech Research Group said that the service lacks features that would ensure a strong challenge in a market dominated by Skype. The feature is yet to be made available via Google's package of business software. Also, users cannot access the feature from mobile phones.

"Given the momentum they've had with Android and the growth of that operating system, it's a pretty clear opportunity and I would expect that's something we'll see in the future," Angl said.

This year, Skype has forged agreements with Verizon Wireless for the installation of its Web-calling software on Verizon phones. For instance, calls on phones such as enV Touch from LG Electronics, can be made without using up wireless minutes.

"We do not offer this feature on mobile browsers, and right now we have no plans to do so," said Randall Sarafa, a spokesman for Google. The company, however, does have Google Voice, a Web-based phone service that lets users take up a single phone number for inbound and outbound calls.

The company may eventually allow enterprise apps customers to access its Web calling capabilities. "We're working on making this available more broadly," said Nick Foster, a software engineer at Google.