For one experiment, Topolinski used a set of number sequences that correspond to positive words, like 54323 ("liebe" -- love) and 373863 ("freund" -- friend), and a set for negative words, like 7245346 ("schleim" -- slime) and 26478 ("angst" -- fear).
The work has practical implications, too. In another experiment, Topolinski had volunteers type numbers that were supposed to go with specific types of businesses; a word that implied the German word for "jewelry" for a jeweler, or "apartment" for a rental office. After dialing the phone number and hearing an answering machine message, volunteers rated the business on its attractiveness. When the number matched the business, volunteers gave the business a higher rating than when they were mismatched; for example, a number for "wealth" for a financial counsel.
Business owners could take this effect into mind when choosing a phone number, Topolinski says. For example, "if you are a lawyer, try to get a phone number which implies the word 'justice,' or if you have a donation hotline, include the sequence 4483 for 'give.'"