Hi
Setup is Snom 300 voip phone. All fine until recently. Haven't changed
and settings on the phone or account. Problem is callers can hear me, I
can't hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.
Paul.
--
Paul McGuinness

"Paul McGuinness" wrote in message
...
Hi
Setup is Snom 300 voip phone. All fine until recently. Haven't changed and
settings on the phone or account. Problem is callers can hear me, I can't
hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.
Paul.

Could be a port-forwarding issue. Did your ADSL upgrade involve
a new router?

--
Graham.

%Profound_observation%

On 01/07/09 21:16, Paul McGuinness wrote:
Setup is Snom 300 voip phone. All fine until recently. Haven't changed
and settings on the phone or account. Problem is callers can hear me, I
can't hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.

I (along with a couple of others on my ISP[1]) had an issue recently
where RTP packets from Magrathea[2]'s media servers were being dropped
by BT's 21CN (which you're likely to be on if you've got non-LLU ADSL2+)
network due to BT's system not liking some sort of priority tagging of
the packets. RTP was fine in the upstream direction, and SIP was not
affected. Symptoms were classic one-way audio of the kind that usually
indicates a NAT/firewall issue, on a NATless network.

If it turns out not to be the usual NAT issues etc, it might be related...


Kim.
--

[1] AAISP, who resolved the issue the following morning after people far
geekier than I were able to narrow it down on their IRC channel.

[2] Sipgate's wholesale provider.

In message , Graham.
writes


"Paul McGuinness" wrote in message
...
Hi
Setup is Snom 300 voip phone. All fine until recently. Haven't changed and
settings on the phone or account. Problem is callers can hear me, I can't
hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.
Paul.

Could be a port-forwarding issue. Did your ADSL upgrade involve
a new router?

Yes, it did. I shall put the old one back on to check it out. If it is
the router, I'm hoping there's some setting on the new one I can tweak.
--
Paul McGuinness

In message , kimble
writes
On 01/07/09 21:16, Paul McGuinness wrote:
Setup is Snom 300 voip phone. All fine until recently. Haven't changed
and settings on the phone or account. Problem is callers can hear me, I
can't hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.

I (along with a couple of others on my ISP[1]) had an issue recently
where RTP packets from Magrathea[2]'s media servers were being dropped
by BT's 21CN (which you're likely to be on if you've got non-LLU ADSL2+)
network due to BT's system not liking some sort of priority tagging of
the packets. RTP was fine in the upstream direction, and SIP was not
affected. Symptoms were classic one-way audio of the kind that usually
indicates a NAT/firewall issue, on a NATless network.

If it turns out not to be the usual NAT issues etc, it might be related...


Kim.
What, if any, was the solution?
--
Paul McGuinness

In message , kimble
writes
On 01/07/09 21:16, Paul McGuinness wrote:
Setup is Snom 300 voip phone. All fine until recently. Haven't changed
and settings on the phone or account. Problem is callers can hear me, I
can't hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.

I (along with a couple of others on my ISP[1]) had an issue recently
where RTP packets from Magrathea[2]'s media servers were being dropped
by BT's 21CN (which you're likely to be on if you've got non-LLU ADSL2+)
network due to BT's system not liking some sort of priority tagging of
the packets. RTP was fine in the upstream direction, and SIP was not
affected. Symptoms were classic one-way audio of the kind that usually
indicates a NAT/firewall issue, on a NATless network.

If it turns out not to be the usual NAT issues etc, it might be related...


Kim.
An afterthought. Skype is working fine. So??
--
Paul McGuinness

"Paul McGuinness" wrote in message
...
In message , kimble
writes
On 01/07/09 21:16, Paul McGuinness wrote:
Setup is Snom 300 voip phone. All fine until recently. Haven't changed
and settings on the phone or account. Problem is callers can hear me, I
can't hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.

I (along with a couple of others on my ISP[1]) had an issue recently
where RTP packets from Magrathea[2]'s media servers were being dropped
by BT's 21CN (which you're likely to be on if you've got non-LLU ADSL2+)
network due to BT's system not liking some sort of priority tagging of
the packets. RTP was fine in the upstream direction, and SIP was not
affected. Symptoms were classic one-way audio of the kind that usually
indicates a NAT/firewall issue, on a NATless network.

If it turns out not to be the usual NAT issues etc, it might be related...


Kim.
An afterthought. Skype is working fine. So??

That is not surprising, one thing that can be said about the Skype protocol
is
that it does not have the same issues as SIP when used behind NAT

--
Graham.

%Profound_observation%

On 02/07/09 00:55, Paul McGuinness wrote:
I (along with a couple of others on my ISP[1]) had an issue recently
where RTP packets from Magrathea[2]'s media servers were being dropped
by BT's 21CN (which you're likely to be on if you've got non-LLU ADSL2+)
network due to BT's system not liking some sort of priority tagging of
the packets.

What, if any, was the solution?

They rolled back the changes made at the ISP end so as not to tag
packets in a way that BT didn't like.

I'm afraid I don't know the technical details.


Kim.

In message , Graham.
writes


"Paul McGuinness" wrote in message
...
In message , kimble
writes
On 01/07/09 21:16, Paul McGuinness wrote:
Setup is Snom 300 voip phone. All fine until recently. Haven't changed
and settings on the phone or account. Problem is callers can hear me, I
can't hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.

I (along with a couple of others on my ISP[1]) had an issue recently
where RTP packets from Magrathea[2]'s media servers were being dropped
by BT's 21CN (which you're likely to be on if you've got non-LLU ADSL2+)
network due to BT's system not liking some sort of priority tagging of
the packets. RTP was fine in the upstream direction, and SIP was not
affected. Symptoms were classic one-way audio of the kind that usually
indicates a NAT/firewall issue, on a NATless network.

If it turns out not to be the usual NAT issues etc, it might be related...


Kim.
An afterthought. Skype is working fine. So??

That is not surprising, one thing that can be said about the Skype protocol
is
that it does not have the same issues as SIP when used behind NAT

I then checked Voipfone and that was working.
Finally after much 'sniffing around' I changed the RTP setting,
'symetrical RTP' from 'off' to 'on'. That fixed the problem. Thanks for
mentioning RTP in your post.
--
Paul McGuinness

In message , Paul McGuinness
writes
In message , Graham.
writes


"Paul McGuinness" wrote in message
...
In message , kimble
writes
On 01/07/09 21:16, Paul McGuinness wrote:
Setup is Snom 300 voip phone. All fine until recently. Haven't changed
and settings on the phone or account. Problem is callers can hear me, I
can't hear them.
On the other hand I have upgraded to ADSL2+. Not sure if that coincided
with the change? Thanks for any help.

I (along with a couple of others on my ISP[1]) had an issue recently
where RTP packets from Magrathea[2]'s media servers were being dropped
by BT's 21CN (which you're likely to be on if you've got non-LLU ADSL2+)
network due to BT's system not liking some sort of priority tagging of
the packets. RTP was fine in the upstream direction, and SIP was not
affected. Symptoms were classic one-way audio of the kind that usually
indicates a NAT/firewall issue, on a NATless network.

If it turns out not to be the usual NAT issues etc, it might be related...


Kim.
An afterthought. Skype is working fine. So??

That is not surprising, one thing that can be said about the Skype protocol
is
that it does not have the same issues as SIP when used behind NAT

I then checked Voipfone and that was working.
Finally after much 'sniffing around' I changed the RTP setting,
'symetrical RTP' from 'off' to 'on'. That fixed the problem. Thanks for
mentioning RTP in your post.
Spoke too soon. The problem is intermittent.
Sipgate help has asked which ports my router is using.

please forward the used ports in your router.

I assume this to mean which ports is my router using for Sipgate.
The Snom log says 5060. So far I have had no further reply.
Any other ideas? What settings in my router could need changing?
As I said before Voipfone works fine, so it's not the Snom, it's not BT
or the new router, it's something else.


--
Paul McGuinness