It happens that Steve in Herts formulated :
> On Tue, 25 Jul 2006 22:49:12 +0100, Jono
> <nothanks@notonyournelly.blueyonder.com.co.uk> wrote:
>
>> Steve in Herts formulated the question :
>>
>>>
>>> Hi,
>>>
>>> I'm not using a router, My Grandstream ATA is connected directly to
>>> my cable modem,
>>>
>>> What is "DMZ" out of interest?
>>>
>>> Cheers
>>>
>>> Steve
>>
>> Your ATA has a router built in <http://www.grandstream.com/y-ht486.htm>
>>
>> DMZ is "De-militarized Zone". In your case, no use looking at DMZ as
>> your ATA is already in the best position in your network.
>>
>> Have you tried any alternative service providers? If you set yourself
>> up with a well known free provider, you could establish (for the most
>> part) where your problem may lie - ring a freephone number to check
>> outbound & call yourself on the geo number to test inbound.
>
>
> Hello,
>
> Yes, as an experiment, I tried using voipcheap with my ATA and I was
> able to place an outgoing call successfully. With voip.co.uk I can
> only receive calls. When I make an outgoing call with voip.co.uk, the
> connection drops almost immediately as soon as the perosn being called
> answers their phone, every time without exception so far.
>
> After 10 days from signing up, I am still trying to get them to sort
> out this problem and they have yet to offer a solution (if one
> exists).
>
> Steve

Bizarre.

They were responsive the one time I had a technical issue.

If anything's likely to be an issue, it's inbound calls usually.

As a matter of interest, if you log in to your account & choose the
link "Your SIP Accounts", does anything look out of the ordinary?

What servers are you using for voip.co.uk? I'm using proxy.voip.co.uk