Modem responds NO DIALTONE when used on a PABX telephone line
Modem responds NO DIALTONE when making a call from a standard BT line
Modem responds NO DIALTONE when making a call from outside the UK
The telephone line I'm using requires BLIND DIALING

Modem responds NO DIALTONE when used on a PABX telephone line
Ensure that the Telephone Lead that you are using is the one that was originally supplied with your modem. Do not plug a substitute lead into the modem. Your modem is a two wire analogue device and will not work on ISDN digital type telephone lines.

Check the telephone line for suitability by using the following procedure. Plug a standard domestic telephone into the back of the modem or into the same socket that the modem was using. If you do not hear dial tone when you pick up the handset then there is a problem with the telephone line.

If you hear a dial tone, use the phone to dial the same number as you were dialing with the modem to ensure that the remote station can be reached. If this works then the modem is probably not dialing because it does not recognise the dial tone produced by the PBX.
For further details see the heading below - The line I'm using requires Blind Dialing.
When using a PBX you may require a pause after the outside line access digit, you can use a comma for this (e.g. 9, 01274 531377).
Modem responds NO DIALTONE when making a call from a standard BT line
Ensure that the Telephone Lead you are using is that which was originally supplied with your modem. Do not plug a substitute lead into the modem.
Plug a standard domestic telephone in to the wall socket that the modem is using and attempt to make a telephone call. If you are unsuccessful then there is probably a fault with the telephone line.
Modem responds NO DIALTONE when making a call from outside the UK
The Pace range of modems are designed and approved for use in the UK.
Should you wish to use your modem abroad, you have to be aware of a number of potential problems.
Approvals, as stated previously, the Pace modems are approved by BABT for use in the UK.
Foreign telephone sockets, we recommend that you use an adapter for your Pace modem to allow it to plug into the foreign telephone socket. These can be obtained from local suppliers such as Tandy or Maplin. Also, TeleAdapt on 0181 233 3000, specialise in the supply of the foreign telephone adapters.
No dial tone, because the Pace range of modems are designed for use in the UK, they will have a problem with the foreign dial tone. To overcome this problem, refer to the next section.
The telephone line I'm using requires BLIND DIALING
Your modem will sample the dial tone prior to dialing, if the dial tone falls out of the specified limits or no dial tone is present the message NO DIALTONE is displayed.
The modem looks for a standard BT dial tone, so if you are using the modem on a PBX or outside the UK or even on a bad quality line you may need to disable the dial tone detect feature. This is done by issuing the command AT X3 to the modem, or including the X3 command in an initialisation string.