DSL and Dial up Modem Issue

[#1]

I wonder if anyone has any knowledge about a problem I am experiencing.  We have just installed an electronic access system at our local village hall.  The system has been set up to allow remote access using dial up modems (USR model 5630B V92) situated at the hall and at my home.  Using this system it should be possible to update the system database  remotely.  We have been struggling for 2 months to get the system working.  We can can dial the remote modem which answers but we cannot get data transfer between my end and the hall.  The computer at my end is dedicated to the task and runs only windows firewall and AVG Ver 8.  The relevant ports are enabled in the firewall.  All system components, software and connections at each end have been double checked.  I have also successfully set up a dial up connection to PN using the pc and modem at my end.
In desperation the installer took the control pc to his home and connected into his fax line.  Lo and behold everything worked as it should .  Significantly his fax line does not have DSL. Hence we are coming to the conclusion that the DSL or possibly the DSLAM at the exchange end is somehow affecting the modem comms.  I seem to recall that some utility companies experienced similar connection problems a few years ago.  Apparently National Grid, water companies etc use dial link into sub stations, pumping stations etc.
Any straws will be clutched.

[#2]

I presume you ARE connecting the USR modem to the 'Phone' side of the ADSL filter ?
If so have you tried changing the filter? Some filters are better than others and it may be that a cheap
and cheerful one is doing a bad job of high frequency filtering and not allowing your modem to work
at 56kbps or so...

[#3]

Have you tried configuring the modems to negotiate a lower speed connection?

[#4]

Yes, the modem is connected correctly at the master socket which is a BT type incorporating the filter.  Also tried connecting directly to the line with the master socket face plate removed.

[#5]

yes. the speed was reduced to 9600 baud with no joy

[#6]

You have stated that the modem at the other end answer and I assume negotiate a connection, i.e. you hear the modem answer and changing tones and then the tones stop. Are you sure that it's not a security feature of the remote access system. For example caller line identification that stop the data transaction?

[#7]

The remote modem is set to auto answer then remain connected.

[#8]

I should have added that security does not depend on CLID

[#9]

if the connection is Via Modem at 9600, should he not be using a filter, shouldnt it be connected straight to a normal phone line?

[#10]

Try reading the first post again!

[#11]

Yes he took the pc to his supplier who connected it to his fax line and it made the connection, that would be a normal line and not adsl

[#12]

That worked - the difference being it didn't have ADSL on that line - i.e. the hall DOES have ADSL.
There should be no reason why it shouldn't work. I have a fax machine on my line and I can use the fax and the ADSL simultaneously.

[#13]

Thanks for the comments.  Just a word of clarification.  The remote end ie the hall does not have ADSL.  We know that the setup there works fine because the installer has successfully dialled in several times using a line which does not have ADSL ie fax line.
My end does have ADSL and that is where the control PC is situated.
Filters serve the purpose of splitting out the high frequency  DSL carrier from the low frequency 'voice'  signal.  A filter must be used on an ADSL enabled line if phones, modems (including sky boxes) or faxes are to be connected as well.  If one of these is connected without a filter it will kill the DSL carrier however if no phones etc are connected no filter is needed.  This is one of the tests you do to determine ADSL faults.
Finally phones etc work just fine without a filter on a DSL enabled line but of course the broadband does not.
If we cannot get this system to work 'as is'  the only alternatives seem to be for me to get a second non DSL line which is expensive or to install ADSL at the hall end which again is expensive especially as we would need a static IP address.  The advantage of that is greater flexibility though. 

[#14]

Quote from: Merlin

we would need a static IP address.

Incorrect.
Dynamic DNS will sort you out.

[#15]

Can the installer access your home phone line via dial-up (or visa versa)?