For national numbers, put the area code between brackets.
In seven-digit numbers, the number is written in two sets of three digits and one set of four digits, or in two sets of three digits, and two sets of two.
Example: (070) 412 3456, or (070) 412 34 56.
Six-digit numbers are written in three sets of two digits.
Example: (0181) 40 81 68.
Write international telephone and fax numbers with the country code, followed by the phone number. The zero in the local area code is left out.
Example: +31 10 408 1775
Write mobile telephone numbers without brackets. Apart from the 6, the digits are grouped in twos. The zero before the 'mobile phone area code' 6 is left out.
Example: +31 6 20 87 45 18.
In contact information, a phone number is indicated as follows: 'tel:' OR capital T, without punctuation. A fax number is indicated by means of 'fax:' OR capital F, without punctuation; a mobile number by means of 'mob:' OR capital M, without punctuation.
Example: tel: (010) 408 1111
T (070) 412 34 56
fax: (010) 408 1111
F (070) 412 34 56
mob: 06 20 87 45 18
M 06 20 87 45 18