SIP Ports

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Me!

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Jun 18, 2022, 9:18:03 AMJun 18
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I am new to VOIP and have just set up a Linksys PPS2T with Vopidiscount.
I have set up both lines with the same account details and both are
working. Just wondering if the SIP Ports for each line need to be
different at the moment I have them both set to 5060?

David Woolley

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Jun 18, 2022, 11:27:11 AMJun 18
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It's going to depend on the ITSP and whatever other means there are for
the Linksys to determine line is being called, but, if the ITSP will
support ports other than 5060, neither should be set to anything
remotely related to 5060, unless you like being called by toll
fraudsters at all hours.

David Woolley

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Jun 18, 2022, 1:00:23 PMJun 18
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On 18/06/2022 17:35, Anthony R. Gold wrote:

>> It's going to depend on the ITSP and whatever other means there are for
>> the Linksys to determine line is being called, but, if the ITSP will
>> support ports other than 5060, neither should be set to anything
>> remotely related to 5060, unless you like being called by toll
>> fraudsters at all hours.
>
> How do these toll fraudsters navigate the NAT that is almost certainly
> employed in the OP's router?
>

The same way as the ITSP does, for incoming calls.

Actually, if he's relying on dynamic NAT, the calls may not be being
sourced from 5060 anyway, although, in that case, various workarounds
will need to be in place, as SIP and SDP expect the port numbers used in
the requests to the ones to actually send to.

If this weren't a real problem, there would not be so much traffic about
using fail2ban with Asterisk.

Me!

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Jun 19, 2022, 3:25:36 AMJun 19
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The VoipDiscount does not have a DID number and is used for outgoing
calls only. Could someone still dial into it? If so I will just leave
the phone on silent!

David Woolley

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Jun 19, 2022, 8:19:59 AMJun 19
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On 19/06/2022 11:24, Anthony R. Gold wrote:
> And what way is that, short of the adapter pre-registering itself? How does
> this ITSP even know which IP address to aim at?

It's generally difficult to stop adapters registering themselves, as the
default use case incoming calls, and they may not have an option to
prevent registration. Some SIP services won't accept calls from devices
that aren't registered, although that is not a requirement of SIP (even
though many users seem to think that registration is a logon, that is
needed before making outgoing calls).
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