What system(s) are you looking at? If it's over the internet (ala Vonage) than the QOS is going to suck, if it's directly from the carrier, might not be so bad since they're most likely using it in the backend anyway. Most likely the endpoints(phones) have builtin QOS, I have an Avaya S8700 system at work that does all of our VOIP, and it's really nice, but the service is the usual copper T1's.

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'02 X5 4.4 - 67k miles
'01 RX300 - Wifey's, 74k miles
'92 325i - My classic (Dinan S1 susp, clears, M3 kit, M3 exhaust, M3 Double-spokes, 216k miles)
'93 318is - Gave to niece