In Sound Which is Better In XM

5700 sounds just average. Between 5310 and 5610, both have great sound quality and are equally good. However 5310 has a 3.5mm jack right on the phone itself while with 5610 you'll have to use the adaptor (provided with the phone). If you're upgrading to either of these phones, i'll recommend 5610 if your budget permits it.

yup get a 5610.. The price difference isnt much and it looks cool too..
But if u want all round functionality then get a 5700.