This is a regularly asked question. I prefer not to initiate texts to my clients (some are discreet and so require absolute discretion from me, and I don’t want to imply I’m touting for business). However I do respond to texts from them that aren’t work related if possible because it’s only polite to reply and I enjoy their conversation. It can cause problems sometimes therefore keeping a professional distance if they make the wrong assumptions about the nature of the relationship!