If you're going to use this as your main equipment in a home office or for a small business, think about the functions you want/need. When there machines first appeared, it seemed that they all did everything (phone, answering machine, fax, printer, scanner) but now the ones advertised in the USA tend not to include all these features.

BTW, if you're using the same landline for voice and fax, I assume that the recognition of dialing tones and fax noises works with Argentina's phone system, especially if you're thinking of purchasing one outside of the country.