What is the legal time to call customers?

As an AI language model, I do not have access to specific legal information about the time to call customers in different countries across the world. However, in general, businesses must be aware of the timing and frequency they use to call customers for marketing purposes. There are several regulations in place to protect consumers from unwanted and intrusive calls. For example, in the United States, the Federal Communications Commission (FCC) has established rules that prohibit telemarketers from making calls before 8 am and after 9 pm in the customer's timezone. Additionally, customers can register their phone numbers with the National Do Not Call Registry, which requires businesses to avoid calling those numbers for telemarketing purposes. Similar rules and regulations exist in other countries as well. Ultimately, businesses must ensure that they comply with the applicable laws and guidelines when calling customers for marketing purposes.