Q: cannot hear incoming calls until activating speaker

Hello friscomitch,

Thank you for using Apple Support Communities. 

I understand from your post that you cannot hear your callers unless using the speaker on your iPhone 5 and when dialing out you cannot hear the phone ring or the caller unless the speaker is on. I know how important it is for you to hear the person you are speaking to without having to turn the speaker on every time. I recommend using the steps in the following article: 

If you can‘t hear a person on a call or voicemail or if the sound isn‘t clear on your iPhone

Best Regards