Vonage and DSL basic

Should be fine if you set Vonage to reduce the upstream bandwidth. It will negatively impact your sound quality slightly, but it's not significant.

I have Vonage set to 50kbs, the medium setting, and nobody notices they are talking on an internet phone.

I've had a few people ask if I'm on a cell (mostly because they're the type of person that would call back on a landline to avoid wasting cell minutes) when I was using lower quality, but it was never an issue.

I have plenty of upstream bandwidth, I was just trying it out for the sake of trying it out.

Vonage was great for me also sound-quality wise, most of the time, and I noticed only very minor differences between the bandwidth settings (most people I was speaking to noticed nothing different). My only pet peeve was the Motorola ATA; it never did QoS right, even if I had the unit first-in-line to my cable modem. If anything else on the network was downloading anything of substance, the audio would get choppy, and THEN people would start to ask if I was on a cell phone. This was on a 4Mbps downstream/1.5Mbps upstream connection, so I doubt the broadband connection was my problem.

I ended up switching to Packet8. The features aren't as refined and polished, but the service is good, and their ATA operates just fine behind my router even if I intentionally place a heavy traffic load on the network. Sound quality is about on par with Vonage at its low-bandwidth setting, but still useable and close enough to toll grade IMO. Again, people I talk to don't notice a difference.

I have both my Cisco ATA and Motorola ATA behind my network firewall (Only the WAN port of the Motorola is connected) -- I have my own QoS which reserves approximately 100Kb of my 1024Kb for VoIP at all times, and offers port-based QoS so that above 100Kb, outbound traffic from the ATAs will be processed before any other traffic.