Well, it's generated in the same way as modern tones are in a telephone exchange, not a played sample. You can usually configure the tone frequencies (never tried on cisco ip phone, but asterisk allows it for its own generated tones and I had a cisco ATA that let you configure them).
So, unless we're limiting ourselves to the original mechanically generated dial-tones. I'll consider them for all intents and purposes to be one and the same.
The comfort noise is also generally only added when there's no other noise on the call. This is to prevent you thinking you were disconnected when no-one is talking.