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I am connecting my iPhone 3GS to my wireless home network using Viber (VOIP). As I am getting poor sound quality as other in the house are downloading, etc. I'd like to create a QoS rule in my router to prioritize VOIP traffic over everything else.

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What is the make/model of your router? – BillP3rd Sep 10 '11 at 18:30
My router is Linksys E3000. – darking050 Sep 10 '11 at 18:33
up vote 1 down vote accepted

The ports which are used by Viber are:

TCP: 4244 and 5242
UDP: 5243 and 9785 

You'll find instructions for configuring QoS in your router beginning on page 36 of the Linksys E3000 User's Guide which you can download from the Linksys support page, or directly from here.

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BillP3rd's answer will help you with setting up QoS, but this will not solve your call quality problem.

QoS will indeed prioritize your traffic, but only up until it hits the gateway. Once it leaves the router and heads towards the first hop, nothing is prioritized any longer. As far as your ISP is concerned, it is all standard data traffic and any tagging your router applies is inconsequential. If your circuit is over-utilized by too much traffic, it will remain that way and you will still have the same problem. You will only solve your problem by limiting bandwidth usage per client through the WAN so that the phone always has a reserved amount in which to transfer data across the circuit. Incoming VoIP traffic will still be fighting for upload speed (say if you have an asymmetric circuit, you may only have a fraction of your download speed set for upload, ie a 6.0/1.0 adsl circuit). If this is the case, then QoS will help a bit, but again, only if he circuit is not being over-utilized.

The fact that you will be connecting wirelessly will also have an effect, as wireless communications with VoIP usually end in some sort of call quality problem. When I worked as tier 2 support for VoIP for an ISP, we would not troubleshoot call quality problems over a wireless connection because there were too many internal variables that could wreak havoc on a VoIP call. Wireless with data isn't as a big a deal, but with VoIP is isn't just about bandwidth, latency can obliterate a VoIP call and you will almost always see higher latency over wireless than wired (in a soho setting anyway).

It is also important to note that everything I have mentioned above will still only affect the VoIP packets on your particular circuit, not when they reach a peered network or the ISP on the other side, so you still may have issues.

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Your Linksys E3000 can run the Tomato firmware.

The Toastman mod in particular has default QoS classes which work effectively without having to modify them.

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