cant dial out

[Muriel9]

Hi my 89yr Mum has a BT landline but can't dial out as it says its busy but she can receive calls, I have asked her to check all the phone are turned off, which she has but we still have the problem, I have done the BT checks and they say there are no issues. 

does anyone have any ideas

[imjolly]

If the phone has answering machine is it possible full of messages. Also check for messages on 1571

[chrisjp]

When you say "it says it's busy" do you mean it is giving what appears to be the engaged tone?
If so, and your mum is on digital voice, this could instead be the "interrupted" tone which signifies that there is a message waiting on the digital voice 1571 service.
As imjolly suggests, key in 1571, listen to the message, and the interrupted tone will go and be replaced with a normal dial tone.