Using the handset I can dial a number, but there is no audible dial tone. Using the speaker gives dial tone and normal conversation. Have I hit the wrong button sequence, or is the machine kaput?

SOURCE: Speaker phone light continually blinks

The blinking light on the speaker button means the forward when busy is on. To cancel it- With the handset on-hook dial #12.
Then press your own station number. Then dial # again. The speaker button should stop flickering.
Note: If the SPK button continues to flicker, Forward all is activated. It is the same process as above but use #11 instead of #12

SOURCE: Dial Tone - Number Dialed does not go through

The problem is possibly the keypad on the phone. Try another phone , preferrably a standard corded phone. If you still cannot break the dial tone, then the problem is with the telephone line (phone company)

SOURCE: No dial tone on handset

It may not be registed with the main unit. You may need to register the handset. With my uniden all i have to do is put it in the main base until it says what handset it is (it should be a number).

If you have any questions please dont hesitate to ask

SOURCE: 1) No dial tone in the handset 2) speaker key will not work

I agree witht this solution, its a common fault, the admin soultion is to find a differnt headset feature access code!

SOURCE: No dial tone in Clarity C4230 setup

if you can get dial tone with another phone, look into manual for any instructions, usually a toll free number for help. ( BEST ) otherwise take phone back for exchange. may be problem in the board.