How do you communicate your Flat Fee rates to clients? Best Practices? Tips?

Update: I am asking regarding people that ask for a rate to be quoted over the phone in an initial call. In person, we of course quote the rates in the meeting.

One of colleagues always quotes his flat fee rates on the phone. And while he does well, he does spend a lot of time on the phone with them discussing the rates.

I usually email the rates or use the firm's texting system to do it, stating that the rates quoted are good for 90 days. This is because I had to many people calling back saying they wanted to hire me, saying I told them a lower rate than I would have ever told them. Also, I will often times send in a form they can fill out, which seems to work very well with motivated clients.

I also see some firms actually post their flat fee rates on their websites, which I feel does not give them enough flexibility to raise the rates for difficult clients or to quote a 'F*ck-Off" rate (which I like to call "Premium pricing to reflect the exclusivity of the service"). Also, I tend to think this makes a firm look more like discount service provider.

Just wondering how others may be quoting flat-fee rates, especially if they have a high volume practice in flat-fee areas.

BTW - We also do a lot of hourly work, but some of the other attorneys are looking toward doing more flat rate work so they can better control their work flow.