You wish to control when folks can get a hold of you. Switchboard allows you redirect phone calls directly to voicemail (which gets emailed to you) so that you can get back to them at a time that works best for you. You also have the option of forwarding incoming SMS messages to your phone or email.
You have signed up for random service X and they are asking for your cell phone number. It may not be in your best interest to give out your real cell phone number to random services just because they insist on providing 2-factor Auth (2FA) via SMS. For some use cases, a Switchboard-managed number might be a reasonable compromise.
Your folks live in another country and it is prohibitively expensive for them to call you on your cellphone number. Get a hold of a Twilio number from that country and manage it within Switchboard. You can then forward those calls (and SMS messages) to your current cellphone.
You wish to put a phone number on your public resume. For folks who don’t wish to give out their personal cellphone number, Switchboard might work best for them.
You need a “Home Phone Number”. As absurd as this sounds, some places still require a home phone number. Give them your Switchboard-managed number instead!
You work at a place that requires you to use a separate work cellphone. This isn’t that great for convenience as you’re probably stuck lugging around two phones everywhere. Using a Switchboard number could allow you to route your calls and messages to the correct phone.
You change cellphone providers more often than most people. Sometimes there are better deals to be had elsewhere, this is a part of the business. The porting in & out eventually starts to become a hassle otherwise you need to update all your new number with all your contacts. A Switchboard-managed number allows you to change your underlying cellphone provider at will!
You manage a small team of support/sales folks and need oversight into which phone numbers your customers can reach them at. Switchboard can help you route calls and messages for each of your numbers to the correct people, thus freeing you from also managing individual cellphone plans. Switchboard also makes it easy to re-route a number in the scenario one of these employees leave.