Just switched from dedicated T1's with analog phone lines to cable modem with 10/2 uplink. We're having some VOIP call quality issues on the outgoing side when bandwidth is stressed and I need to setup QOS or a VLAN on our RVS4000 router.

Currently all phone traffic (talkswitch device and ip phones) are on it's own d-link PoE switch, and all workstations are on a LinkSys 1GB switch. Both switches are plugged into ports on the RVS4000. I'd like to set it up so that the dlink port has ~512Mbsp dedicated to it for voice at all times. It's my understanding that with a VLAN or QOS I can set this up.

I've got QOS setup already with port 5060 to have high priority but it doesn't seem to make a difference.

  • I don't think the question can be answered really. This link helped me as I used Tomato and it works. Not sure how well RVS4000 QoS works for VOIP. linksysinfo.org/index.php?threads/…. I'm using a Mikrotik router now and that has excellent QoS features. – Matt Jun 26 '12 at 3:54

At a guess, your problem isn't LAN-side but on the cable modem. If you have 10 Mbps down and 2 Mbps up, you have slightly more outbound bandwidth than with the T1 link, but you are likely having more jitter and generating more outbound traffic. I'd suggest putting QoS on the cable router (or the link to the cable router), guaranteeing a portion of the bandwidth for VoIP.

Depending on packetization interval and protocol used, you're looking at roughly 30 kbps to 90 kbps per simultaneous call.

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port 5060 is only for setting up the call. All the actual voice traffic is on a range of ports which varies. You need to setup port based QOS for the port your SIP devices are connected on. Usually UDP 10000-20000 but this can be defined on the SIP server/clients.

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