Thanks Travis for your prompt reply. I need to do some more research to find an app which will allow me to call from my iPad. I'm still a newbie with an iPad having acquired it from Virgin a couple of months ago. Cliff
After checking, the iMessage would of came through due to a voicemail being received on another iPhone logged in with the same AppleID as you have n your iPad. It's impossible to access voicemail on iPad.
I have an old MacBook Pro early 2011 which is now obsolete. It has not been used for sometime although it has the latest compatible macOS High Sierra (10.13.6) on it and will be converted to a Win10 laptop soon. However, it did appear in my iCloud account and will again if I connect it to the internet.