Einstein famously said "Reality is an illusion."
And, like it or not, the illusion people have of us is who we really are - at least for them. Perception is reality.
So what can we do to ensure that this perception is in line with our reality? That the way we see ourselves is how we are actually experienced by people?
The famous psychologist Albert Mehrabian is widely misquoted as saying that the way we look (body language, facial expression) counts for 55% of the impression we make on people; 38% is down to how we sound (tone and quality of our voice); and only 7% comes from what we actually say, the words we use.
What he actually said was that if there is incongruence between these three elements we'll believe the look more than the sound, and the sound more than the words. So if someone says "I'm really excited" in a dull monotone with a long lifeless face, we're likely to believe that they are in fact feeling the very opposite of excited!
If there's incongruence between your 'visual, vocal and verbal' you are leaving yourself open to interpretation. This can all too often be mis-interpretation, with people thinking negatively about you. So for example you may feel relaxed (slouched comfortably in your chair, arms and legs crossed) but be interpreted as arrogant or indifferent; or you may be feeling nervous (stiff body, avoiding eye contact, staying silent) and be experienced as cold, bored, hostile even.
Try the phone and mirror test
Next time you're on the phone, check yourself in the mirror. Is the meaning you want to communicate with the words you're saying reinforced by how you look and how you sound?
Play around with your expression (smile, eye contact, gestures ...) and the modulation in your voice to ensure they are congruent with the meaning you want to convey.