microphone doesn't pick up sound when in speaker phone.
When using the iphone 5 in speaker mode, the mic won't pick up my voice when trying to talk to the person.
iPhone 5, iOS 6.1.4
Basic troubleshooting steps outlined in the manual are restart, reset, restore from backup, restore as new. Try each of these in order until the problem is resolved. If you've been through all these steps and the trouble persists, you'll need to bring your phone to Apple for evaluation. Be sure to make an appointment first at the Genius Bar so you won't have a long wait.
Best
GDG