Perhaps you had heard about Telecoil and had wondered, what is it and how it works and what are the benefits of this feature. First we will start with basics, this feature is mainly designed for people with Hearing Aids and a telecoil, or know as t-coil is a small copper wire that is built into the hearing aid. This tiny wire function is to pick up the signals from the called a loop system, and this system what does it’s to amplify the audio in public areas, so hearing aid users can listen the environment or announcements. The most common examples of places with this feature will be airports, movie theaters or even on place of worship and can be easily noted with the symbol that we have before.
The best person to tell you if you need Telecoil would be your hearing aid provider as they are the most knowledgably people to talk about this as is not just if you want it out of the blue, however they will give you the benefits of this, which makes a lot of sense to get it as it helps like in the next scenarios:
Helps to people with severe or progressive hearing loss to be aware of surroundings in public places or even the use of the phone.
If a person with hearing loss works in specific places such as courtrooms, or entertainment venues and they are constantly on the phone.
A person simply wants to have a better and accessible solution to hear in general in public and to have a pleasant sound experience.
A nice feature of the Telecoil found inside the hearing aids is that thanks to it the sounds of a speaker’s voice for example is streamed directly in the ear without unwanted background noises, a common example of when a person appreciates this feature can be if they go to the movie theater and they can hear the dialogs in the movie without having any issues. Depending on the model of the hearing aids some of them have the telecoil feature on all the time so no need to deal with settings, another ones they have the the on/off setting for this setting. This switch is commonly called the T-switch. Telecoil is not going to be found in all hearing aids, the smaller the device is the most likely will not have that feature due to the small size of it, for example the completely-in-canal and the invisible-in-canal devices will not have Telecoil and mainly will be based on microphones for its use.
With that being said, as many people with hearing aids are required to work on a daily basis and use common telecommunication devices such as desk phones and headsets, manufacturers had applied their best engineering and technology to help them with their devices. Poly, Cisco and Yealink among others offer their desk phones with Hearing aid compatible handsets, this means that the person will not have any feedback when using the desk phone during a call.
Poly, formerly known as Plantronics offer a wide range of corded and wireless headsets for 
users in 
an office environment and compatible from desk phones to computers and cell phones. For a desk phone solution we can find the HW510 headset or the HW520 for a corded solution, while if want a wireless option for your desk phone there 
is the Savi 7210 and Savi 7220. If in need on something to use with your desk phone and computer,
the EncorePro headsets would be, only thing would be a PC Switch like the MDA 100 or the MDA 524, while on a wireless option would be the Savi 8210 or the Savi 8220.
Jabra offers their GN2125 Noise Canceling Telecoil headset Hearing Impaired, this headset 
actually works as a single ear headset as one of the earcups will be completely mute, allowing the user to focus their attention in
the speaker where the sound is coming from. The GN2125 can be used as a corded solution for your desk phone with the use of the GN1200 smart cord or you can use the Link 860 amplifier if want to use with the desk phone and the computer.
As you can see there is a full lineup of devices that are Telecoil hearing aid compatible and now that we had explained why the Telecoil meaning and benefits now hoping everything makes more sense for people with hearing aid and without them.
