CJE’s ADSL FAQ

Question Index

• What is ADSL?
• Can I use the same line for my ordinary phone calls?
• Can I use the same line for a modem or Fax machine?
• How long does it take to have ADSL enabled on my phone line?
• What is a ‘Contention ratio’?
• But 512Kb/50 would be slower than my old 56K modem wouldn’t it?
• Can I connect my PC to ADSL as well as my RISC OS computer?
• Can some mail go to my PC and other mail to my RISC OS Computer?
• Can I still use ArcFax with ADSL?
• I already have a network but it is 10base2, can I connect to ADSL?
• I have a number of phone sockets do I need any more than one microfilter?
• Why would I need a Firewall?
• Why can’t I buy a router from a PC box shifter?
• Do I need to choose an ISP that gives me a static IP address?
• Don’t I need DHCP as comes with RISC OS Select?
• Some ISPs supply a USB ADSL modem in their initial charge, can I use it with a USB podule?
• What is a ‘Wires only’ service?
• What is a microfilter?
• Do I have to pay anything to BT?

The Questions

Q.  What is ADSL?
A.  ADSL stands for Asymmetric Digital Subscriber Line because it involves the transmission of data in digital form. ADSL technology uses ordinary copper telephone wire to transmit data at broadband speeds of up to 8Mbps downstream and 1Mbps upstream.

Q.  Can I use the same line for my ordinary phone calls?
A.  Yes, provided you plug the phone in via a microfilter(q.v.) (available from CJE)

Q.  Can I use the same line for a modem or Fax machine?
A.  Yes, provided you plug the modem or Fax machine in via a microfilter(q.v.) (available from CJE)

Q.  How long does it take to have ADSL enabled on my phone line?
A.  Pipex & F2S are currently quoting 7-10 working days

Q.  What is a ‘Contention ratio’?
A.  When ordering from your chosen ISP you will be offered a 50:1 or 20:1 contention ratio. This is the number of other users who you ‘share’ your 512K bandwidth with.

Q.  But 512Kb/50 would be slower than my old 56K modem wouldn’t it?
A.  Yes that is true, but that assumes everyone is using their connection flat out all the time our connection (CJE) is on a 50:1 ratio and we have found our connection has so far never been slower than about 400Kb/sec.

Q.  Can I connect my PC to ADSL as well as my RISC OS computer?
A.  Your PC can be setup to access your ADSL alongside your RISC OS computer so long as you use a router with a built-in hub or router and separate hub.

Q.  Can some mail be directed to my PC and other mail to my RISC OS Computer?
A.  Yes, provided you are using seperate POP3 mailboxes. You can then fetch from the appropriate mailbox on the appropriate computer.

Q.  Can I still use ArcFax with ADSL?
A.  Yes, but you would still have to use ArcFax through your existing modem. You can connect the modem to the ADSL phone line by using a microfilter(q.v.).

Q.  I already have a network but it is 10base2, can I connect to ADSL?
A.  To use your existing 10base2 network, you will need to use a hub with a 10base2 connection. You then use 10baseT to connect the router to the hub, and connect your 10base2 network to the 10base2 connection on the hub.

Q.  I have a number of sockets already fitted around the house/office. If I plug the microfilter(q.v.) into the ‘Main’ phone socket do I need any more than one microfilter(q.v.)?
A.  Theoretically, yes you only need one microfilter(q.v.), but you would then have to wire it so that all the other sockets are plugged into the microfilter(q.v.). This could mean unwiring the cable from the master socket that goes to the other sockets and fitting a 6pin BT631A (standard BT phone plug) to the cable (not recommended).

Q.  Why would I need a Firewall?
A.  A firewall allows you to closely control the traffic on your router. This allows you to prevent access to your computer from the outside world (eg. hackers) and also to prevent access to certain areas of the internet from your computer. A firewall is probably not necessary if you are running a standalone or very small network, but if you have a large network, then it is certainly advisable to setup a firewall.

Q.  Why can’t I buy a router from a PC box shifter?
A.  Most routers are setup via a web browser interface. Unfortunately, many of them use forms of JavaScript which are not compatible with current RISC OS browsers and so require connecting to a PC. Some routers have a serial port console built in where they can be setup using a comms package on RISC OS. It is important to buy a router which you know can be setup easily on your RISC OS computer. We sell routers which we know how to set up, and which can be setup by RISC OS computers.

Q.  Do I need to choose an ISP that gives me a static IP address?
A.  No the router can use a static or dynamic IP address

Q.  Don’t I need DHCP as comes with RISC OS Select?
A.  No, using a router means this is unnecessary.

Q.  Some ISPs provide a USB ADSL modem in their initial charge, can I use that with a USB podule rather than a router?
A.  When the podules and suitable drivers are available and using DHCP from RISC OS then yes a USB ADSL modem could be used in place of a router, but this would give ADSL access to only one computer and that computer may also be more susceptible to outside hacking.

Q.  What is a ‘Wires only’ service?
A.  A ‘Wires only’ service means that the ADSL line is set up at the exchange and that there is no need for any modification to your home phone connection.

Q.  What is a microfilter?
A.  A microfilter is a small device that sits between the phone socket and any phones/fax machines/modems you wish to connect through the ADSL line.

Q.  Do I have to pay anything to BT?
A.  The only thing you have to pay to BT is your normal line rental and for any non ADSL phone line usage e.g. phone, fax.