Teléfono - Tel.
On second thought, I usually put only Teléfono if it is at the end of a letter,or in the heading.
If it is a business card I even abbreviate this:
Tel. +1-832-358-2097, or
(+(1-832) 358-2097 where
+ is the access to international calls
(00 in Argentina, 011 in United States,it varies from country to country.
1 is the country code for the USA (54 for Argentina, this is different for each country).
832 is the area code
and 358-2097 is the local access number.
In Argentina some people instead of putting Tel. place a very small drawing of a phone and then the number. This drawing occupies about the size of 2 or 3 fonts.
Hope it helps.
Local time: 09:01
Native speaker of: English, Spanish
PRO pts in pair: 2664