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Comcast phone service

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  • 1.  Comcast phone service

    Posted 07-09-2019 19:18
    I have Xfinity internet with voice. I know that the phones jack are on the modem. I have been using a modem without the jacks but I still have the service. My question is...

    Will the voice protocol be routed properly even though it is required to have the jacks in the modem?

    Wouldn't I need IP phone service for srx usage.

    I have just bought the right modem because Xfinity will only allow it this way.

    Will it route properly if the jacks in the modem are not there. Will I get service problems?

    I am referring to overall service issues.

    I'm not referring to trying to use phones on the srx. As I said, it's required to use the right voice modem.

  • 2.  RE: Comcast phone service

    Posted 07-09-2019 22:11



    Per this, Xfinity Voice is a digital phone service known as VoIP (Voice over Internet Protocol).


    So, if you already have  Xfinity voice, we don’t need any other “IP Phone service” for making calls.

    ALG (Application Layer Gateway ) on the SRX should take care of the voip traffic. 

  • 3.  RE: Comcast phone service

    Posted 07-10-2019 04:59
    My question is this.

    I know how the Xfinity voice phone service works but what if I'm not using the voice modem with jacks?

    I'm currently using a modem without any phone jacks but the Xfinity service for voice/phone is still running.

    Will it cause overall service issues.
    Will the srx still operate properly
    because the signal is going through
    the srx and not to the phone jacks?

    It is required to have a voice modem.

    I'm not trying to see if it will operate
    properly through the srx. I know it won't.
    But will it disrupt my internet connection?

    It is designed to work with voice modems with jacks only.

    But will the srx still ROUTE OUT the traffic properly? Or will it cause internet service problems?

  • 4.  RE: Comcast phone service
    Best Answer

    Posted 07-11-2019 18:28
    I have concluded that the mentioned scenario does have problems when the voice modem is not used but the service is running. I live in a static environment in terms of electrical service. If it were a dynamic service maybe it would not be as apparent. Either way the srx will not route out the traffic properly I believe. These VoIP phones cannot be used on the srx. They must be used on the voice modem themselves. That's Xfinity for you. The upside is the forwarding of traffic at that level. It provides forwarding of the whole network. I suspect the forwarding is not as disjointed as regular land line for phones. The use of h323 and others is an overall plus. Forwarding was important to me in my locale.

  • 5.  RE: Comcast phone service

    Posted 08-20-2019 05:21
    I want to apologize for a misstatement in this post. "Either way the srx will not route out the traffic properly I believe. " That statement is incorrect. I have found a way to properly filter out the traffic even though this service from Comcast says a voice modem with jacks is required to run the service. The srx does not operate properly with that voice modem. It has external internet traffic that cannot go through the SRX. I used a non-voice modem and filtered out the traffic.