IOS – iPhone not sending / recieving links

Without knowing more details, I cannot know this for certain, but it seems likely that your father's wife is receiving iMessages sent to him, but not SMS text messages. This is the designed behavior – iMessages are delivered to an Apple ID, and if they share an Apple ID, iMessages will go to both of them. The solution is for them to not share an Apple ID.

That said, one can set up a different Apple ID for Messages but keep the same Apple ID for the App store, iTunes, etc. This would alloow them to share purchases, but keep their messages separate from each other.

You can also go into Settings > Messages > Send & Receive and un-check mark the email address that is associated with both of their phones (and Apple IDs). There is a good chance that will also fix your problem.

It doesn't have to do with your Number, it's a known Bug which happens to all iPhone Android switchers.

It has to do with the way Apple has made its iMessage service.

Thanks to an ongoing issue with the way Apple built its iMessage platform, users who switch away from an iPhone to an Android phone or any other cell phone are faced with a huge problem: once they bail on the iPhone, they often can’t receive text messages from contacts who are still using iPhones. This is because Apple’s system still sees them as iMessage users, and it tries to deliver messages sent using Apple’s Messages app as iMessages. To make matters even worse, the iPhone users who send those messages see their status as “delivered” even though they are not being received.

source http://bgr.com/2014/05/19/fix-imessage-iphone-bug-android-sms/.

i hope this will help you.