What are good routers to setup QoS between two NEC Aspire KSU's for offices with T1s.

I have two offices that are connected with T1 lines (not Point to Point)  I currently have the two offices connected with (2) Sonicwall tx150 routers that have a VPN setup between the networks.  The (2) NEC Aspire KSU phone cabinets are connected across the VPN to allow intercom between the two offices.  We only have about 1-2 intercom conversations at any time.  We have light data traffic across the VPN for terminal services, mail server.   The intercom works great most of the time but once and a while we get broken voice (jitter?) when I have found that there is data transfer.  I have done tests with IPERF utility and have found my upload and download speed across the VPN is about 750 kbs.

I understand that Quality of Service (QoS) may help me. I understand that there is no guarantee if I am using the open internet and don't have a PtP T1.  Not looking for perfection. I find the current Sonicwall routers can't do Qos.  I was wondering what routers I should look at?  I was looking at the Cisco 871.  Is a Cisco router too hard for a novice to learn how to program, especially QoS.  Also looking to learn more about QoS on routers.  Any links with good info?