Switching between iMessage and Text

My query relates to two people having iPhones and who have iMessage enabled. Now, imagine a scenario where one person cannot connect to a WiFi network or mobile data, and wants to send a 'text' message to the other iPhone user. I know that a text message can be sent to another person when the phone is connected to a network and if the message is not delivered to the other person. But, my problem is that if the phone is not connected to any network/mobile data, it does not allow the user to send a text. It displays "Cannot Send Message: iMessage needs to be enabled to send this message". I have tried searching this problem, and the 'workaround' is to turn off iMessages from 'Messages' settings menu. I tried this and I still get the same error. I cannot send a text message to a person with whom I've been exchanging iMessages with, in two situations: a) If I'm offline and b) If I've turned off iMessage. There are a few people who have suggested creating two contacts, one for the phone number and the other for the apple id used to iMessage of the other person. But, these are merely a 'workaround', but do not represent a precise solution. Is there something I'm missing out? Is there an easier way to solve this issue?