There may be times when it's easier for you to make or take calls by speakerphone on your iPhone. In iOS 8, you can set up the speakerphone for individual calls, or when you want to listen to voice mail messages. If you prefer, you can also set your iPhone to default to speakerphone, so that it automatically handles all incoming and outgoing calls in this mode.
Using the Speakerphone in Calls
You can turn on your iPhone's speakerphone when you make a call and the recipient answers, or when you accept an incoming call. In both cases, a menu screen appears on your iPhone. To switch to speakerphone, tap the "Speaker" button which turns blue when activated. To turn off the speakerphone at any time during a call, tap the button again. You don't need to turn it off at the end of a call, as it switches off automatically when the call is done.
Using the Speakerphone to Listen to Voice Mail Messages
You can also listen to voice mail messages on speaker. When you have a new message, tap the "Phone" and then "Voicemail" buttons. Select the message you want to hear and tap "Speaker" under its playback controls. Its blue text turns to a blue box to show that the speakerphone is on. Once you have activated it on one message, all your messages will use this playback method -- it doesn't turn off automatically. To turn it off, go into a message and tap "Speaker" again.
Set the Speakerphone as the Default
If you prefer, you can set the speakerphone as your iPhone's default answer mode so that all incoming and outgoing calls use the speaker. Tap "Settings" and then "General." Open the "Accessibility" option, locate the Interaction section and select "Call Audio Routing." Tap "Speaker." When the tick appears in the Speaker line, tap "Accessibility, "General" and then "Settings." Tap the "Home" button at the bottom of your iPhone to return to your main screen. If you want to go back to regular answer mode or to switch to a Bluetooth headset, repeat these steps and tap "Automatic" or "Headset" in the Call Audio Routing screen.