[VoiceOps] Issues with ISPs blocking SIP 5060 - 5061

J. Oquendo sil at infiltrated.net
Thu Nov 21 08:36:31 EST 2013

On Wed, 20 Nov 2013, Jay Hennigan wrote:

> I haven't run into any blocking, but we're seeing more and more
> instances where the larger carriers will install some sort of NAT router
> as the handoff on residential and small business accounts as opposed to
> giving the customer a DHCP or static public IP.
> Many of these devices horribly break SIP, especially if you're putting
> any kind of ALG behind them.
> Getting the carrier to turn off all of the cruft and just give you raw
> access to the Internet is often an exercise in futility.

We have seen a lot (A WHOLE LOT) of this occurring with
Comcast. E.g., we have a client with multiple PBXs spread
through about a dozen or so locations throughout CT, RI, MA.
At least once per quarter, Comcast seems to push out some
form of policy/rule/firmware update or other that prohibits
the connection via VoIP and ONLY VoIP. This particular
account uses Comcast business however, when this occurs, we
get a call from this client, and see the trickle effect via
our other clients (ATAs, softphones, etc.)

Most other providers we deal with, could care less
(Covad, Paetec, AT&T) however the cable providers (which
RoadRunner is another) seem to be horrible at this game
(filtering). "Getting the carrier..." We try not to inherit
any of the network unless we are managing it. This frees us
from any liabilities associated with say a Doctors office
doing some whacky VPN to a hospital or other. Would take us
too long to perform a network assessment, and make sense of
a client's business needs, especially for free.

J. Oquendo

"Where ignorance is our master, there is no possibility of
real peace" - Dalai Lama

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