If we have someone's phone number, we can contact them and try to engage them. If we have just their email address, we can send them a message, but then we need for them to respond. If we never get their phone number, emails are going to be the only form of communication that can ever occur.
People need to get our phone number from us for this same reason. As aging-in-place professionals, we generally work with an older demographic, and they are accustomed to speaking with people by telephone. Even if we were talking about younger people, they like to text rather than talk on the phone - but they still need a phone number for texting.
Consider the power of having someone's phone number (or for them to have ours). There are four ways that someone can contact us if they have our phone number. The same is true if all we have is the potential customer's phone number. Other types of contact information are important, but the phone number is essential.
With just the phone number - and no name or email - we can call someone and speak with them or leave them a message. We can text them, or they can notice that we called and return it. Thus, the four ways a phone number can result in an actual contact that furthers the sales process is (1) call and speak to the person when they answer, (2) call and leave a voice message when no one answers, (3) text a message to the phone number, and (4) the missed call will show up in their call log and a return call may occur.
As long as we get to speak to the person we are calling - whether it happens when we place the call or later when they return our call - we can deliver our message and pursue an appointment and the sale. Even we don't get to connect with the person we are attempting to call, we have three other ways of eventually getting to speak with them. It takes them responding to our invitation, but the phone number is still the pivotal player.
Also, we aren't limited anymore to just calling someone at home and reaching them there. The cell phone has greatly enhanced our ability to reach people by phone - especially when they are away from home or beyond traditional business hours. Also, we don't have to be concerned about whether they might be home before calling them.
If we only have someone's phone number, and we call and happen to engage them on the phone, we can ask for their name again (or for the first time) and for their email address. It might be a little awkward or embarrassing, but we can do it. At least we would be speaking with them. Again, this underscores the importance - and the power - of having someone's phone number. And, if we have a choice, get their cell phone number.