Apple phones sending my Android phone iMessage by default now, and I won't receive the message

I recently put my SIM into an iPhone 4 as my Android phone (OnePlus One) was giving me problems. I promptly switched back to my OnePlus One, but now it seems that every time someone with an iPhone tries to send me a message, it sends using iMessage. I would assume this is happening because I put my SIM inside an Apple product. I think there are ways around this by asking the person who's sending me the message to switch their setting to sending just normal messages to me, but I feel like it's quite inconvenient to, first, ask if they have an iPhone and if they do, teach them how to send using regular text message.

Is there any way I can fix this or am I stuck with this problem?