I have the exact same question. At one point it forced me to think why can't i use the same vonage adapter with the xfinity voice service. But i beleive that one might be locked to be used with vonage only, with the phone number inbuilt into that adapter box which connects phone with the modem. If that is the case, how come such adapters are available on the market ? Can you buy any of them and use it for voip ?
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