It is proper Netiquette to do business during business hours. Don’t use your phone for business all the time.
Work Netiquette Smartphones
Smartphones have a lot of business applications. The many applications that smartphones provide allow users to work and do business at all hours. Reading emails is work.
Responding to emails is doing business in cyber space. Do business in cyber space during business hours for credibility and accountability.
Limit business use to business hours because setting boundaries is healthy.