Last week a squad of urban commandos armed with stencils and power hoses crept out late at night to imprint the five digits of Ireland's lesser known directory assistance service on pavements around the city centre.

"When you're the third player in the market [after Conduit's 11850 and Eircom's 11811] you have to be a challenger brand and push boundaries to get noticed, " said 11890 managing director Nicola Byrne.

The idea to utilise the grime of the capital's streets to imprint the number in pedestrians' minds by scrubbing a patch of paving clean came from a conversation Byrne had with advertising firm DDFH+B three years ago. She said she spotted a similar power-washed stencil advertising Becks beer on Dublin's Camden Street last summer.

"We've been careful to do this only on certain streets and avoided stencilling in front of listed buildings. We went through the bye-laws ourselves and couldn't find any problem with it, " said Byrne.