Learn how to make calls on your iPhone 6. Making a call on iPhone is as simple as choosing a number in your contacts, or tapping one of your favorites or recent calls. Or just ask Siri to “call Bod Jones”

• Add favorites. With Favorites, you can make a call with a single tap. To add someone to your Favorites list, tap + icon. You can also add names to Favorites from Contacts. In Contacts, tap Add to Favorites at the bottom of a card, and tap the number to add.
• Delete a name or rearrange your Favorites list. Tap Edit.
• Return a recent call. Tap Recents, then tap the call. Tap i icon to get more info about the call, or the caller. A red badge indicates the number of missed calls.
• You can also reach recent and favorite people youve been in contact with from the multitasking screenjust double-click the Home button.
• Dial manually. Tap Keypad, enter the number, then tap Call.
  • Paste a number to the keypad: Tap the screen above the keyboard, then tap Paste.
  • Enter a soft(2 sec) pause: Touch “*” key until a comma appears.
  • Enter a hard pause (to pause dialing until you tap the Dial button): Touch the “#” Key until a semicolon appears.
  • Redial the last number: Tap Keypad, tap Call to display the number, then tap Call again.
• Use Siri or Voice Control. Press and hold the home button, say the name or number. You can add “at home,””work”or”mobile” See How to use Siri. See How to use Voice control.
• For best results, speak the full name of the person you’re calling. When voice dialing a number, speak each digit separately for example, “four one five, five five….” For the 800 area code in the U.S, you can say “eight hundred”
• Call over Wi-Fi. (Not available in all areas. iPhone 5c, iPhone 5s, or later.) To route calls over Wi-Fi, go to Settings > Phone, then turn on Wi-Fi Calling. On iPhone 6 and iPhone 6 Plus, if the Wi-Fi connection is lost, calls switch automatically to your carriers cellular network using VoLTE (Voice over LTE), if available. (VoLTE calls also switch to Wi-Fi when a Wi-Fi connection becomes available.) On earlier models, a call is dropped if you lose the Wi-Fi connection. Contact your carrier for feature availability.
• Call from your iPad, iPod touch, or Mac. Tap or click a phone number in Contacts, Calendar, or Safari, or from a recent contact in the multitasking screen. The device must be connected to the same Wi-Fi network and, along with your iPhone, signed into FaceTime and iCloud using the same Apple ID. Both iPhone and your other device must have iPhone Cellular Calls turned on at Settings > FaceTime. Your iPad or iPod touch must be using iOS 8; your Mac must be using OS X Yosemite. (On iPhone, make sure allow WI-Fi calls is turned off at Settings > Phone > Wi-Fi Calls) The call is made via iPhone, which must be on and connected to a cellular network. Cellular charges may apply.

When someone calls

• Tap Accept to answer an incoming call. Or if iPhone is locked, drag the slider. You can also press the center button on your headset.
• Silence a call. Press the Sleep/Wake button or either volume button. You can still answer the call after silencing it, until it goes to voicemail.
• Decline a call and send it directly to voicemail. Do one of the following:
  • Press the Sleep/Wake button twice quickly.
  • Press and hold the center button on your headset for about two seconds. Two low beeps confirm that the call was declined.
  • Tap Decline (if iPhone is awake when the call comes in).

Note: In some areas, declined calls are disconnected without being sent to voicemail.

• Respond with a text message instead of answering. Tap Message and choose a reply or tap Custom. To create your own default replies, go to Settings > Phone > Respond with Text, then tap any of the default messages and replace it with your own text.
• Remind yourself to return the call. Tap Remind Me and indicate when you want to be reminded.
• Take a call on your iPad, iPod touch, or Mac. Click or swipe the notification to answer, ignore, or respond with a quick message. The device must be connected to the same Wi-Fi network, and signed into FaceTime with the same Apple ID, as your iPhone. Both iPhone and your other device must have iPhone Cellular Calls turned on at Settings > FaceTime. Your iPad or iPod touch must be using iOS 8; your Mac must be using OS X Yosemite. (On iPhone, make sure Allow Wi-Fi Calls is turned off at settings > Phone > Wi-Fi Calls). The call us received via iPhone, which must be on and connected to a cellular network. Cellular charges may apply.

Keep it quite

• Want to go off line for a while? Swipe up from the bottom edge of the screen to open Control Center, then turn on Do Not Disturb or Airplane Mode. SeeHow to use do not disturb.
• Block unwanted callers. On a contact card, tap Block this Caller (you can see a callers contact card from Favorites or Recents by tapping). You can also block callers in Settings > Phone > Blocked. You will not receive voice calls, FaceTime calls, or text messages from blocked callers. For more information about blocking calls, see support.apple.com

While on a call

• When youre on a call, the screen shows several call options.
• End a call. Tap or press the Sleep/Wake button.
• Use another app while on a call. Press the Home button, then open the app. To return to the call, tap the green bar at the top of the screen.

Respond to a second call. You can:

• Ignore the call and send it to voicemail: Tap Ignore.
• Put the first call on hold and answer the new one: Tap Hold + Accept
• End the first call and answer the new one: When using a GSM network, tap End + Accept. With a CDMA network, tap End and when the second call rings back, tap Accept, or drag the slider if iPhone is locked.
• With a call on hold, tap Swap to switch between calls or tap Merge Calls to talk with both parties at once. See How To use Conference calls

Note: With CDMA, you cant switch between calls if the second call was outgoing, but you can merge the calls. You cant merge calls if the second call was incoming. If you end the second call or the merged call, both calls are terminated.

Call forwarding, call waiting, and caller ID

• Set up call forwarding, call waiting, or caller ID. (GSM) Go to Settings > Phone.
  • Call Forwarding: The Call Forwarding icon appears in the status bar when call forwarding is on. You must be in range of the cellular network when you set iPhone to forward calls, or calls wont be forwarded.
  • Call Waiting: If you’re on call and call waiting is turned off, incoming calls to voice mail
  • Caller ID: For FaceTime calls, your phone number is displayed even if caller ID is turned off.
• For CDMA accounts, contact your carrier for information about enabling and using these features. See support.apple.com

Note: Refer here for more information on iPhone 6.