There is obviously nothing wrong with political parties wanting to communicate with voters. However, to answer your specific question about whether the parties should have access to telephone numbers or other personal information, I would say that the notion of consent should come into play, given the principles of privacy. If an individual's phone number is not public and that person does not want to disclose it to anyone, including a political party, it should be possible for them to keep that number confidential.
On April 17th, 2018. See this statement in context.