There are plenty of synonyms for the phrase "sign customer up" that can come in handy for sales and marketing professionals. Some alternatives to consider include "enroll customer," "register customer," "join customer," "initiate customer," "onboard customer," "bring aboard customer," "recruit customer," "procure customer," "enlist customer," and "secure customer." These phrases can be useful when describing the process of acquiring a new customer or client, and can help salespeople differentiate their approaches when pitching their products or services. Whatever the phrasing, the goal is always the same: to bring new customers into the fold and generate business.