My iPhone and my iPad are ringing at the same time when I receive a FaceTime call.

Many users use a free gmail.com email address for FaceTime and iMessage on their iPad.

Using FaceTime http://support.apple.com/kb/ht4319

Troubleshooting FaceTime http://support.apple.com/kb/TS3367

The Complete Guide to FaceTime + iMessage: Setup, Use, and Troubleshooting

http://tinyurl.com/a7odey8

Troubleshooting FaceTime and iMessage activation

http://support.apple.com/kb/TS4268

iOS: FaceTime is 'Unable to verify email because it is in use'

http://support.apple.com/kb/TS3510

Using FaceTime and iMessage behind a firewall

http://support.apple.com/kb/HT4245

iOS: About Messages

http://support.apple.com/kb/HT3529

Set up iMessage

http://www.apple.com/ca/ios/messages/

iOS and OS X: Link your phone number and Apple ID for use with FaceTime and iMessage

http://support.apple.com/kb/HT5538

How to Set Up & Use iMessage on iPhone, iPad, & iPod touch with iOS

http://osxdaily.com/2011/10/18/set-up-imessage-on-iphone-ipad-ipod-touch-with-io s-5/

Set Up Alert Sounds

http://www.quepublishing.com/articles/article.aspx?p=1873027&seqNum=3

Extra FaceTime IDs

http://tinyurl.com/k683gr4

Troubleshooting Messages

http://support.apple.com/kb/TS2755

Troubleshooting iMessage Issues: Some Useful Tips You Should Try

http://www.igeeksblog.com/troubleshooting-imessage-issues/

Setting Up Multiple iOS Devices for iMessage and Facetime

http://macmost.com/setting-up-multiple-ios-devices-for-messages-and-facetime.htm l

FaceTime and iMessage not accepting Apple ID password

http://www.ilounge.com/index.php/articles/comments/facetime-and-imessage-not-acc epting-apple-id-password/

Fix Can’t Sign Into FaceTime or iMessage iOS 7

http://ipadtutr.com/fix-login-facetime-imessage-ios-7/

FaceTime, Game Center, Messages: Troubleshooting sign in issues

http://support.apple.com/kb/TS3970

Unable to use FaceTime and iMessage with my apple ID

https://discussions.apple.com/thread/4649373?tstart=90

iOS 7 allows you to block phone numbers or e-mail addresses from contacting you via the Phone, FaceTime, or Messages

http://howto.cnet.com/8301-11310_39-57602643-285/you-can-block-people-from-conta cting-you-on-ios-7/

How to Block Someone on FaceTime

http://www.ehow.com/how_10033185_block-someone-facetime.html

My Facetime Doesn't Ring

https://discussions.apple.com/thread/4155326

How to watch FaceTime calls on the big screen with Apple TV

http://www.imore.com/daily-tip-ios-5-airplay-mirroring-facetime

Send an iMessage as a Text Message Instead with a Quick Tap & Hold

http://osxdaily.com/2012/11/18/send-imessage-as-text-message/

To send messages to non-Apple devices, check out the TextFree app https://itunes.apple.com/us/app/text-free-textfree-sms-real/id399355755?mt=8

How to Send SMS from iPad

http://www.iskysoft.com/apple-ipad/send-sms-from-ipad.html

How to Receive SMS Messages on an iPad

http://yourbusiness.azcentral.com/receive-sms-messages-ipad-16776.html

Apps for Texting http://appadvice.com/appguides/show/apps-for-texting

You can check the status of the FaceTime/iMessage servers at this link.

http://www.apple.com/support/systemstatus/

 Cheers, Tom 😉

You can answer it on either one. If you don't want them to come to one of the devices go to Settings > FaceTime > Receive At and adjust to taste.

You can select which address/number you want to use per device in Settings > FaceTime.

If wherever is calling you has both your number and email on your contact in their apple device, then it will continue to ring on both until you answer or decline on one of the two.

The only way to prevent this is have the caller make two contacts for you. One with your email and one with your phone number. And make sure your iPhone is using the phone number only and your iPad is using the email only isn Settings > FaceTime.

Let me know if you have any further questions. Good luck.

Expanding a little on deggie's answer, you can similarly go to Settings>Messages>Send & Receive and also adjust to your own preferences. Do this on your iPad and what you will probably want to do is uncheck the option to receive at your phone number. Then have a play and make sure you're happy with the results.