If they're sending you texts - SMS messages, using SMS protocol - you should receive them. If they're sending you iMessages (the default) you won't receive anything - Android can't do iMessage (since Apple owns the protocol and won't allow Google to use it). If you switched from an iPhone to an Android, and didn't remove your iPhone from iMessage before you switched, all the texts are going to your old phone (IOW, the garbage can). (The fix for the last one is a trip to a Genius Bar.)