The iPhone can switch between two calls and Apple makes it easy to manage either. If a beep is heard while already on a call it might mean someone is calling. Of course, trying to figure out what to do while in the middle of a conversation can make the user feel rushed and uncomfortable. Understanding how this works in advance can make it quick and nearly effortless to manage two calls at the same time.
Handling multiple conversations on a single phone isn't a new innovation. Known as call waiting, this handy feature first appeared in the 1970s, long before the first iPhone was invented. The technology was made possible by electronic switching machines and made life much simpler when on a long call but expecting another at any moment. Modern technology just makes this easier and an iPhone user is less likely to accidentally hang up, which was common with old landline phones.
Apple has provided a convenient way for the user to manage two conversations at the same time on a single iPhone by putting one on hold and answering the second. When a second call comes in while using the Phone app, a tone will sound periodically as a way of alerting the user of the incoming call. Glancing at the iPhone, several options will appear to help manage the second call. End & Accept hangs up the current call and answers the new one. Hold & Accept places the current conversation on hold so the person on the other end can't hear while answering the incoming call. It's also possible to decline the income call and continue the first discussion. If keeping both conversations active, a Swap button makes it easy to switch back and forth between two people.
Using Two Lines On An iPhone
It's also possible to use call waiting on two separate telephone lines if the iPhone has dual-SIM support and both are activated. This allows both work and personal lines, with two separate numbers, to be used on one iPhone without missing calls. In this case, Wi-Fi calling must be enabled for at least one of the lines. This option is found in the Settings app under the Phone tab.
Whether using a single phone number with your iPhone or dual-SIM, the Call Waiting feature must be switched on. This option is found on the same Phone settings tab and should be green, indicating that call waiting is enabled. These options are switched on by default, but this is the place to check if troubleshooting is needed. With call waiting and easy switching between calls, the iPhone helps make sure every call that's wanted goes through.
Source: Apple