If you're looking for synonyms for the phrase "call up", there are several phrases and idioms that can be used interchangeably. Some popular phrases include "ring up", "phone", "dial", "reach out to", and "contact". Other common idioms include "give a buzz", "send a message", "reach out", and "get in touch". Each of these phrases can be used in a variety of contexts, whether you're talking about making a phone call, sending an email, or reaching out through social media. With so many synonyms available, it's easy to find a phrase that works for your specific needs and circumstances.