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voice adaptor for motorola SB6121

Posted by
Regular Visitor
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Member Since: ‎10-13-2009
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Message 1 of 2 (6,636 Views)

voice adaptor for motorola SB6121

I have switched to Comcast Voice from Verizon.  I have a Motorola Surfboard SB6121 cable modem that I own.  I need to buy an adaptor to go with this modem to facilitate voice service.  The outsourced Comcast voice chat person told me I needed an "ethernet chord" to make this work.  I googled ethernet chord and then realized that the person meant cord not chord.  At any rate;  there is some sort of adaptor that I can purchase or rent that will allow me to hook my home phone system into my existing modem.  Anyone know which one I need?

Posted by
Cable Expert

Member Since: ‎03-02-2007
Posts: 17,639
Message 2 of 2 (6,625 Views)

Re: voice adaptor for motorola SB6121

For CDV you need what is called a eMTA which is a telephony modem.  There is no adapter for your existing unit.  A eMTA does both CDV and HSI.


You have a few choices:


Keep your existing modem for HSI and add a rented eMTA for CDV.  Rented eMTA's from Comcast are $7 a month in most area's. 


Unhook the existing cable modem and add a rented eMTA for both HSI and CDV for $7 a month.


Unhook the existing cable modem and in some area's you can buy a eMTA.  This is not a nationwide program.  Select Best Buy's with Comcast Connection Centers have these D3 Arris TM722G for sale.  The list of stores is HERE  They are $150 plus tax & the cost of a Comcast tech to come out and install it.  If your area is listed, look for the Comcast Sales Rep in the BB TV section with the red or black shirt.