Hi Jason
QoS is always important when dealing with VoIP, but as you only control the flow as traffic leaves your switch at home and then at the remote end, you will always be "fighting" the internet for bandwidth/priority if your ADSL line is a home user setup. The QoS on your local switch will help guarentee/prioritize the traffic that leaves your home network, but after that, it's a free for all untill it hits your remote end. If the 2900 is the XL, then you will have scheduling capabilities, see below for more details.
In summary, yes, apply the QoS at your end and the remote end, this my help the "quality" of the call, but you also need to factor in the Codecs you are using and that you are using VPN protocols to get to your remote end.
2900 XL QoS
The Catalyst 2900 XLswitches with 8 MB of DRAM provide QoS based on IEEE 802.1p Class of Service (CoS) values. They support input classification and output scheduling. The Catalyst 3524-PWR XL and 3548 XL switches also support the p...
