Anyone who has played this game knows there is frequent confusion and mistakes when calling out the score before a serve. A lot of confusion is not about the score itself, but about the server – 1 or 2.
There is a simple way to avoid most of it. Instead of calling out "one" or "two" for the third number, call out "first" or "second". This clearly differentiates the server number from the score, and makes it obvious that the call refers to the server. I have tried this method several times and found it very helpful in clarifying the scoring during a match.
Of course there are many people who would not want to change, either out of habit or preference. The call of "one" or "two" would still need to be acceptable.