Dial tone gone strange today not constant like it should be

[#1]

The phone does not seem right today, the dial tone is not constant anymore but was ok yesterday.
only way i can explain it on here would be like this
beep stop beep stop beep stop not a constant dial tone like it should be.
Is someone messing with my line?
I can make calls but i wont be making any while it has this odd thing going on.

[#2]

It probably means that you have a voicemail.
If you dial 1571 you should be able to retrieve it.

[#3]

Thanks for the fast response, Does it cost anything to retreave the voicemail?
I think i will turn this feature off to as we have an answer machine on the phones and the rest of the family i used to using it this way.

[#4]

No, it's free.

[#5]

Thanks James it was a voicemail but the family are just not used to them as we have answer machine on the phones so i have decided to disable the feature