iPhone: Understanding phone features

iPhone supports many features, including call waiting, call forwarding, and conference calls, but certain features on iPhone behave differently on GSM and CDMA networks.

You can use different methods to turn on these features, depending on your wireless carrier's network technology (GSM or CDMA):

Feature iPhone (GSM networks) iPhone (CDMA networks) Notes
Call forwarding Turn on or off in
Settings > Phone.
Contact your carrier for information on using Call Forwarding.  
Call waiting Turn on or off in
Settings > Phone.
Contact your carrier for information on using Call Waiting.  
Caller ID Turn on or off in
Settings > Phone.
Contact your carrier for information on using Caller ID.  
Conference calls Supports up to five calls simultaneously Supports up to two calls simultaneously. CDMA networks may not be able to add, swap, or merge calls in certain situations. See the iPhone user guide for more details.
Dial a soft pause Tap and hold * when you dial. When you edit a contact number, tap +*#, then tap "pause." Inserts "," into a phone number and waits a few seconds before dialing the additional digits.
Dial a hard pause Tap and hold # when dialing. When editing a contact number, tap +*#, then tap "wait." Inserts ";" into a phone number and waits for the user to tap Dial before dialing the additional digits.
Place a call on hold Tap and hold Mute. N/A You can't place a call on hold on CDMA networks.

Learn more about differences using cellular data networks, including LTE.

When you use an iPhone on a CDMA network, you may notice these differences:

  • Contacts or phone numbers on webpages that contain alphabetic characters beyond seven digits may not dial as expected (for example, 1-800-MY-IPHONE or 555-1212x1234). You can either remove the additional letters or use a pause to dial the extension (555-1212,1234).
  • The following features may not be available on iPhone on CDMA networks:
    • Enabling a SIM PIN
    • Importing SIM contacts
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