While at the company, Mr. Kravitz, 38, began writing on Twitter under the name Phonedog_Noah, and over time, had amassed 17,000 followers. When he left, he said, PhoneDog told him he could keep his Twitter account in exchange for posting occasionally.
The company asked him to “tweet on their behalf from time to time and I said sure, as we were parting on good terms,” Mr. Kravitz said by telephone.
And so he began writing as NoahKravitz, keeping all his followers under that new handle. But eight months after Mr. Kravitz left the company, PhoneDog sued, saying the Twitter list was a customer list, and seeking damages of $2.50 a month per follower for eight months, for a total of $340,000.