
The agency has run into problems as its New York shop, TBWA\Chiat\Day, already handles the ad account for Vonage, a rival internet phone-service brand.
Vonage appointed TBWA\Chiat\Day to its ad account in April, and it's thought that the company has now taken issue with the Skype appointment.
Omnicom, the parent company of TBWA\Worldwide, is currently in the process of negotiating a solution with Skype, with possible alternatives including setting up a conflict shop to work on the account.
Skype appointed a global roster of agencies last month. Along with TBWA\London, it also appointed Rapp to handle its CRM and eCRM business, and Wolff Olins to handle its global creative strategy.
The news has come just one week after Tim Lindsay, the UK president of TBWA\Group UK, left the agency.
He has been replaced by Robert Harwood-Matthews, the managing director of PHD West in the US.