"Professional"

L (who is new in our office) told us the following -

He talked with the colleague of the other department, and he told her that she could call his mobile at any time.

He thought that he works professionally and he wants to solve all her doubts and questions regarding to the project.

However, the female colleague looked at him in a very strange way and said "Are you sure?"

L immediately realised that his expression might be misleading, and both of them were embarrassing.

Actually, it is a matter of culture, and he still needs to take time to adjust.