Point to be mention in appointment letter - Social media, personal calls, mobile usage strictly prohibited

i am little bit confused how can mention below point in appointment letter please help me
1. office timing 9 am to 6 pm (change in timing unless change by management)
2. Social media, personal calls, mobile usage strictly prohibited

Hi There,
You can mention as a different clauses
Timings:
Office timings would be as per the Schedule - 1. Any changes/ Adhoc additions will be communicated by the management prior to the shift.
Mobile Usage:
Usage of Mobile Phones for Personal Calls, Social Media or any other activity apart from official usage is prohibited.
Thanks,
Akash