Q: Why won't iMessage send from my iPad to a contact who has an iPhone and uses iMessage on her iPhone?

The recipient may have their iPhone not using WiFi at the time you send the message, and iMessage may not be supported by the cellular carrier the recipient is using.

If you sent the message iPhone to iPhone, in those cases, the message would be converted and sent as an SMS text message.  But an IPad is not a cellular telephone - it cannot do this conversion.

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 6 and OS X Mountain Lion: 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/

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

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/message/19087457

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

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

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

 Cheers, Tom

Just had same problem from my iPad Air and solved it. My iPad does not have cellular, so only works on wi-fi. Therefore I cannot text (which is cellular) so only sending iMessages from my iPad to other iMessage (Apple) devices. When I could not get any "messages" (iMessages) delivered from my iPad to a particular contact who has an iPhone & whom I was previously able to message from the iPad, I had him check and he found to his surprise that the iMessage setting on his iPhone was turned off ( perhaps after doing an update). He was getting texts (cellular) from my iPhone to his iPhone, but not messages from my iPad to his iPhone because somehow the setting for iMessages was turned off on his iPhone.  Hope this helps you as it did solve my situation.