Telephone Number Usability

To display a UK telephone number to potential callers inside and outside the UK, people often use the format

+[country code] ([trunk prefix])[area code] [local number]
e.g. +44 (0)1234 567890

The trunk prefix is something you only have to dial within the UK (it’s considered part of the area code internally), hence the separation, but this approach is problematic. Do international callers know to omit the 0? It’s particularly confusing as parentheses are generally used around the area code elsewhere. And do UK callers know to either omit the +44 and include the 0, or include the +44 and omit the 0?

I’m not convinced it’s clear and helpful for anyone; something like (+44/0) 1234 567890 would at least try to convey the either/or nature of the information.

Anyway, I’m going to stop using it. I propose the following alternative approaches:

Overwhelmingly UK-based audience

([trunk prefix][area code]) [local number]
e.g. (01234) 567890
Omit parentheses for national/mobile numbers

Truly international (no strong UK bias)

+[country code] [area code] [local number]
e.g. +44 1234 567890

Mixed (perhaps mainly UK but significant international element)

Both of the above, clearly labelled
e.g. UK Tel.: (01234) 567890, International: +44 1234 567890

For business-to-business or a tech-savvy audience you can get away with using just the international format slightly more often (people are increasingly putting all numbers into their mobiles and computers in international format so they’ll work when travelling or using VoIP).

Does anyone know where the (0) approach comes from? Like so many things, it’s firmly established but doesn’t make sense once you stop and think.

Fri 13th Oct 2006, 1:32pm GMT

Filed under: Hints and Tips, Marketing and Advertising, Offline, Rants and Grumbles, Usability

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