Hi idealist...have you tried to put the phone number in without the 1 in the front?
Dunno what this means. But I just tried putting in my mobile number on the iPad via my contacts, and it says "[number]" is not registered with imessage(?) It offers either "remove" for the number, or to use my email address. Not what I want to do.
[Also, on your iPhone, make sure that it is set to receive under your phone number. Go to iPad settings/imessage and see where the designation is to "receive at." Check to see what your settings are and re-test. Let us know if it works.]
On the ipad, the settings say to receive at my email address. I can add another email, but there is nowhere I can see to add my phone number.
When I look at my phone, it says "You can be reached for messages at:
Please no personal info on posts: moderator removed info...
The "1" is the international prefix for the United States and Canada. Skimonkey didn't realize you are in Oz, where your prefix is +61. Here, in North America, it is normal to quote your number in 11 digit form starting with 1, whereas in other countries, only the local number is used.
Can't help with the actual question, since I don't have a data plan for my Ipad. I just use my email address to send and receive iMessages on the iPad, although I use my phone number to do it on the iPhone. Both work OK.