VoIP firm Jajah has hit out at eBay for telling users in some countries that they are not allowed to use Jajah's new Buttons program on the site.

Buttons allows Jajah users to place a customisable button into auctions on eBay, eBay Stores and eBay Motors which allows bidders to call sellers before they buy.

The service is available in 122 countries and connects both parties via phone-to-phone and does not require any special software or a headset.

An eBay email to sellers using Jajah's Buttons stated: 'The listing was removed because it violated the eBay Inappropriate Links policy. Links or other connections to live chat systems are not permitted.'

Roman Scharf, co-founder of Jajah, said: "With millions of registered users, Jajah is hardly an 'inappropriate' organisation.

"We were seeing great excitement for Jajah Buttons on eBay and we are disappointed that some of our users' listings are now being removed.

"We are currently seeking clarification from eBay as the situation varies from country to country. While we get positive feedback from within eBay in several countries, we see other countries removing listings that contain Jajah Buttons."

A spokeswoman for eBay explained that the application was banned because the site requires that all interactions between buyers and sellers happen inside the marketplace.

Some critics have suggested that the online auction giant has restricted Jajah as it is a rival to Skype, which it owns.

Skype suffered an embarrassing outage in August, during which Jajah subscriptions jumped by 50 per cent, while poor financial reports prompted the resignation of Skype chief executive Niklas Zennström last week.