schedule the appointment via email, but they insist on a phone conversation prior to the meeting. They can get a feel for the client that they don't get via email. I don't think the absence of a phone number is a red flag, just the way some providers prefer to do business.

making an appointment.  I'm OK with that, and sometimes I've had real nice conversations with them.

Mostly however appointments are set up by email.  I do insist on them giving me a phone number at least a day before we meet so I can reach them or they me in case of a last minute hitch.

because I can leave a message any time convenient for me...  she can answer at her convenience...   once we approach setting a time, need to switch to phone.  
skb

email is the only option a gent has to initiate contact with me. i request certain very specific information in my ads, and expect to find that information in his initial email. one of those things is a personal phone number, so that i can call him (at a time convenient for him) and we can get to know one another. i do not accept "appointment" requests in an initial contact, because those are not the types of men i wish to attract (someone who wants a wham bam with a total stranger). so, after the initial email which should include his real name, age, race and a phone number AND most importantly the exact nature of his needs and interest in me in particular...then i will follow-up by email confirming a phone call and that starts a phone/email relationship where we each feel each other out and determine compatibility. then when everything feels right, a meeting is planned. and even then, i do not provide a phone number. i only provide a phone number to men i have seen and who wish to see me again (and again).

I also believe that a live phone number for both is required for the last mile up to the appointment.

I assume you're using the initial email only until someone is screened, and then they can email or call for future appointments.

I think it is important to be clear about communications up front. I think email only (no voice or text) is fraught with problems for both folks. An email only appointment requires the lady to provide her location further in advance. Maybe not an issue for repeat clients.

Also, often for email a lady relies on the hotel WiFi for her internet which may/may not work.

I had a recent encounter with my ATF that illustrates the pitfalls of modern communication devices: She was taking the train from NYC to the DC area for our meeting. She accidentally left her cell phone in the cab in NYC. I was unable to call her when I arrived and after some time was concerned about an NCNS. I happened to check my hobby email and had gotten an email from her explaining the situation. However, she was also having serious issues with her laptop connecting to the hotel WiFi network.

Yes, thats a case of email saving the day, but what if I did not have a smartphone and data plan?

I think any methodology can work, as long as everyone is clear on how to connect. I think the "email only for initial contact" is fine and maybe even a good idea. It sounds like the issue you had was not the initial part, but that he continued to use only email.

can not always answer my (hobby) phone.

When I'm at home, my wife and kid are there. When I'm at work, my employees are there. I have no privacy most of the time and would have to make excuses to step outside to make hobby phone calls. I can check emails any time, anywhere.

when a provider WON'T use e-mail.

Pimps, robs, circuit girls, often won't use email, for a variety of bullshit excuses.

I prefer e-mail overall. However, I won't provide references unless I have spoken on the phone with the provider. That's just one of my 'things.'


HalfHour

My ATF will not give out her phone #.  Says she never has.  Reportedly, this keeps her personal life and hobby life comfortably seperate.  All contact is via e-mail.  She calls me shortly before a meeting to confirm via a blocked # and has never let me down so I suppose I can't complain too much.