updated list of steps to try.
NOTE: some people are still posting that these steps have not worked for them and that apple has stated this is a known issue and are STILL working on it even after the update that was supposed to fix it.
http://support.apple.com/kb/TS5185
http://support.apple.com/kb/HT5759?viewlocale=en_US
before calling applecare to have ur # unregistered by them:
if u have the old iphone still, turn off imessages and facetime.
if u do not have the old iphone still, text "STOP" to 48369. this should prevent anything apple wise from being associated with ur apple id at all.
both steps take up to 24 hours. please wait until those 24 hours are up until continuing with further steps.
if u did at least one of the 2 steps above, waited 24 hours, and ur iphone using contacts still cant text u:
call applecare at (1-800-275-2273) and have an apple advisor revoke the # out of the imessage/facetime system. if u followed the previous steps then it should already be out of the system but it never hurts to check with apple itself.
have ur contacts update their software to ios 7.1 (or later, if available when this is read) as apple posted a fix for the iphones not receiving notifications about contact's imessages being turned off/revoked and are therefore still sending imessages.
if that doesnt work then have ur contacts turn off imessage and turn it back on. this should update the change with ur contact info. while they are in the correct page also have them make sure that they have send as sms turned on in settings>messages.
if THAT doesnt work, then have them delete every conversation they have with u in it, delete u as a contact, and then re-add u and try to start a new conversation.