"Por" in this context basically means "as" - so, it literally means something like "as a favor". So, it would mean "Could you do this as a favor for me?", though it is usually translated as "Please", since it is more common in English to say that.
On the other hand, "para favor" or, more gramatically correct, "para el favor" would mean "for the favor", which doesn't make much sense, since you are expected to do a favor to benefit a person, not to do something to benefit the favor!
por favor llame para
Haz esto para mi por favor.
por favor puedes enviar este fax para mi
por favor, espere unos minutos para las intervenciones
It means, "Give me time to think, please."
por favor pague para el almuerzo de lauras
No toque means "do not touch" in Spanish.
por favor
"Por" translates (more or less) to English "for".
Por favor explica mejor tu pregunta para poderle ayudar.
"Me gustaría una cerveza helada"
Silencio, por favor. Tranquilo, por favor. Podrías guardar silencio, por favor?