But don't count on it. Try to learn at least a little Spanish, even if it is choppy or your accent is tremendously bad, and use it when you can. They really appreciate the fact that you are willing to appear less than competent in order to make them feel more comfortable. According to Mexican laws, and common sense, you must translate your marketing literature, product manuals, labels, and warranty. The telephone is a useful tool to set up appointments and ask some general inquiries, but deals are never closed over the phone.
Telephone is considered an informal means of communication.
It is also recommended that you confirm all appointments over the phone. They are preferred over the phones when dealing important issues. In most cases when phoning a Mexican businessperson, you will have to go through 1-3 secretaries before reaching the desired person. These secretaries may not speak English, so have a short sentence prepared. Mexicans invariably want to look you in the eye during business negotiations and you can't do that over a telephone line.