It's both handy and simple to be able to have your phone calls rerouted to another number, but if Apple makes it easy to set up, it doesn't let you do the kind of advanced features that would make this so much more useful.
There are plenty of reasons to have more than one phone number, and when you do, there are as many reasons to want to answer them on a single phone. Apple's iOS 12 lets you forward any call to any number you like, and to do so at any time. However, there are specific limitations that make this feature less useful than it should be.
You have to set up Call Forwarding while you are in an area with a cell signal. That is specifically only when you're setting it up, though, as after that you can even turn the phone off completely and forwarding will still work.
On your iPhone, go to Settings, scroll down and tap on Phone. Then tap on Call Forwarding.
You'll get a new screen that has a single option on it, called Call Forwarding, and an on/off toggle that will be set to off. Turn it on, and now you get a second option labelled Forward To.
Tap on the arrow to the right and you'll get a numeric keypad. Unsurprisingly, this is where you enter the phone number you want your calls forwarded to. Surprisingly, you have to enter a number, you cannot just pick from your contacts list.
Even more surprisingly, there's nothing like a Save or a Done button.
You just enter the number and tap the button to go back.
That's it, you're set. Depending on your number and your location, you may find that your iPhone converts it to an international number, but otherwise, the number you entered is there to stay.
Except when it isn't. We sporadically found that if, for some reason, you force quit System Preferences, the number might vanish. So don't do that.
That's it, but that's all
So it's not as if it's hard to set up Call Forwarding, but you've already seen the first limitation — you can only forward to one number. If you need to forward calls to a different number on Tuesdays, well, you know what you've got to do every Monday night.
For many, possibly most, iPhone users, though, there is another immediate limitation. You can switch Call Forwarding on or off, but you can't get it to work after a few rings.
That's called Conditional Call Forwarding and it's the ability to tell your iPhone that if you haven't answered your phone after so many rings or so much time, it should then forward the call to somewhere else.
We're not blaming Apple for leaving this feature out for most people as it's at least as much down to the individual carriers.
If your carrier does support it, though, the way you activate Conditional Call Forwarding is something out of the stone age. It requires you phoning a specific number, set by the carrier and including code commands like #67*.
You know that if Apple handled this, they'd have a simple on/off switch. But aren't handling it, so they don't.
Shortcuts and Do Not Disturb
Even with the limitation of having a single number you can forward to, and even with whatever conditional forwarding limitations carriers impose, there is more that Apple could do.
When you turn on Do Not Disturb from Control Center, for instance, there is already a lot of intelligence built in about switching it back on at the end of an event, or when you leave a location. There should surely be a way to have Do Not Disturb include a Forward Calls option.
That could be a simple on/off switch in the Do Not Disturb options, especially as — after you've entered a number once — Call Forwarding itself is just a simple on/off toggle.
That's controlling a setting on your phone, it doesn't require any more facilitating from the carrier. Nor would expanding the Phone options in Siri Shortcuts. Right now, just about the only thing you can do is have Shortcuts ring a number that you pass to it.
Even making it possible to turn on Call Forwarding via Shortcuts would mean you could build routines. If a call comes in while Do Not Disturb is on, and it's during office hours, reroute the call to your assistant or colleague.
Take it and leave it
All this said, though, it is good that you can leave your iPhone at home while you're abroad on vacation and know that the calls will all go through to your manager.
Although if that thought just gave you pause, the way it did us, we might now have another idea for something Apple could add to this.
We'd like Selective Call Forwarding. Just reroute calls from specific clients and not, say, the partner who can't seem to remembers that you told them never to call you at the office.