Visitor
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xfinity blocking SIP traffic in gateway
i have a grandstream HT802 adapter to use with a 3rd part voip provider and ported my xfinity number to it.
it was work fine for several weeks so i then cancelled the viop service from xfinity.
at that point the the adapter stopped working and i am no longer able to make or receive calls
that fact that it worked until i cancelled the service suggests that xfinity is explicitly blocking this traffic once i stopped paying them for the service.
is that the case and is there a way to have them not do so?
(i enabled port forwarding as suggested by the voip provider but that did not help.
this forum suggests turning on bridge mode but i have wifi extenders so don't want to do that.
the viop provider also suggested modifying the SIP ALG setting but there seems to be no way to do that,
i also tried disabling the firewall.)
is there a way to get xfinity not to block SIP traffic?
XfinityPeterH
Official Employee
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2.8K Messages
6 hours ago
Thanks for the detailed explanation. Xfinity is not intentionally blocking third‑party VoIP traffic after canceling phone service, and canceling Voice alone does not cause SIP traffic to be blocked.
Tthe most likely causes are related to SIP handling on the network path rather than billing or service cancellation. Common triggers include changes that occur when Voice service is removed, such as routing changes, NAT behavior updates, or how SIP sessions are handled upstream.
SIP ALG is still the most common cause of this behavior. Even when the modem is customer‑owned, SIP ALG can exist on routers or other network equipment and can interfere with VoIP registration and call setup. Port forwarding, disabling the firewall, or DMZ settings typically do not resolve SIP ALG issues.
If possible, we recommend:
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EG
Expert
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117.8K Messages
1 hour ago
@user_7qzlec
If this is an Xfinity-rented gateway device, AFAIK it can't be disabled. One way to deal with the SIP ALG option is to configure Xfinity-provided Gateway into bridge mode, and get your own router that has SIP ALG as an available and configurable feature. Good luck !
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