for iOS 9.1 software

Large phone keypad
Make phone calls simply by tapping entries in your contacts and
favorites lists. When you need to dial a number, the large numeric
keypad on iPhone makes it easy. See .
LED Flash for Alerts
If you can’t hear the sounds that announce incoming calls and other
alerts, you can have iPhone flash its LED (next to the camera lens on the
back of iPhone). This works only when iPhone is locked or asleep.
Note: This is a great feature for all users who, when in a loud
environment, may miss the tones associated with calls, texts, and other
alerts.
Turn on LED Flash for Alerts. Go to Settings > General >
Accessibility > LED Flash for Alerts.
Call audio routing
You can have the audio of incoming or outgoing calls automatically
routed through a headset or speaker phone instead of iPhone.
Reroute audio for calls. Go to Settings > General > Accessibility > Call
Audio Routing, then choose how you want to hear and speak your calls.
Make a call