On or At a Telephone Number

[iamwkk]

I have heard that it should be "on" but found that "at" is also very commonly used.....which one is correct? or both are acceptable?

Eg:

1) Please call me on 123-456-7890
2) Please call me at 123-456-7890
3) Please call me on this extension

Thank you.

[Tdol]

In British English, 'on' is more common.

[Ouisch]

In AmE, it's more common to say "call me at ----" If you're at work and have an extension number, you'd say, "Call me at 313-559-1640, extension 250."