The important point about remote microphones that work with hearing aids is compatibility. Traditionally, hearing aid manufacturers did not use an industry standard to communicate with the hearing aids directly. They used a proprietary communications protocol. This meant that you could only use products that came from the manufacturer (or a licensed third party) for your accessories. The problem is if you ever want to replace your hearing aid with a different manufacturer. All your accessories will most likely NOT work with another product. This is why using other "standard" hearing assistive technology (HAT) was more desirable. The products could be used with any hearing aid manufacturer. Since the aids would not receive a signal directly, there needed to be a way to get the signal to the aids. The telecoil was the way to do it. It required the hearing aid to have a telecoil and you used a neckloop to get the signal to the telecoil. Today, the new hearing aids have the ability to receive a standard Bluetooth signal without the use of another device. The Resound hearing aids use a modified Bluetooth (BT low energy) that was developed with Apple to get the iPhone signal directly into the Resound aids. To receive a standard Bluetooth signal, such as from an Android phone, you need an accessory (phone clip plus) to get the signal to the aids.
Confusing, but should get better if the hearing aid industry settles on a standard.
Tony in Michigan