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I am making the switch to VoIP. I chose voip.ms as my service provider and Mediatrix 4102 as my ATA.

One reason why I chose the Mediatrix over other popular consumer ATAs is that it's supposed to be easy to place it in front of the router, so it can give priority to its own upstream traffic over the home network's upstream traffic. This is supposed to work transparently, with the ATA and router sharing the same public IP address (the one obtained from the modem).

They call this feaure Transparent IP Address Sharing, or TAS. Their promotional brochure describes it like this:

The Mediatrix 4102 also uses its innovative TAS (Transparent IP Address Sharing) technology and an embedded PPPoE client to allow the PC (or router) connected to the second Ethernet port to have the same public IP address, eliminating the need for private IP addresses or address translations.

I am interested by this feature because my router, an Apple Time Capsule, doesn't support QoS and cannot give priority to the voice packets if the ATA is behind the router.

However, after hours of searching the web, reading the documentation, and good ol' trial and error, I haven't been able to configure the Mediatrix to run in this mode.

Then I found a version of the manual that looks like it was for a previous version of the firmware (SIP), where there is an entire section dedicated to configuring TAS (starting at page 209).

But my Mediatrix comes with the DGW 2.0 firmware, whose documentation does not mention TAS at all.

So I tried to follow the TAS setup instructions from the SIP documentation and apply them to my DGW firmware, using the Variable Mapping Between SIP v5.0 and DGW v2.0 document as a reference, but no success. Some required SIP variables don't have an equivalent in DGW.

So it looks like the DGW firmware does not support TAS at all, or if it does they are not doing anything to help us set it up.

So right now, the Mediatrix is behind the router and VoIP works perfectly except when my upstream bandwidth is saturated.

My questions are:

  1. Is downgrading to SIP firmware the only way to have my Mediatrix 4102 run in TAS mode? If not, anybody knows how to setup TAS on the DGW firmware?
  2. Is TAS mode the only way to give priority to the voice packets if I want to keep my current router (Apple Time Capsule)?

Thanks!

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1 Answer

up vote 1 down vote accepted
  1. From now, TAS is not supported by the Dgw 2.0 application. Yes, you can probably downgrade to Sip 5.0 application, but I do not recommend this approach
  2. No, you can also put the 4102 directly on the internet connection and configure the local firewall and dhcp server. You can then connect your time capsule behind the 4102.

Good luck

Simon

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Thanks! For setting up the 4102 in front of my router, do I also need to enable and configure the NAT service on the 4102 and disable NAT on the Time Capsule, or can my time capsule still be the NAT? –  Pascal Bourque May 25 '12 at 18:21
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