Also if you make him your Dom he wants you to call him at the end of the night but there is no landline option for that.
I did pull this up and was able to get an option in the bedroom. Like the domme half, it only applies if its the evening (since that is when you tell me to do it). Try heading to the bedroom in your last time period. If that doesn't work, you may have already done something with him that day. Try heading back in the evening the next day to see if it appears. (The requirements on that are that he is in sub mode, he's been ordered to make the call, it's evening, and he's not in recharge mode, which happens after some scenes and goes away during the night)