You seem to be mainly interested in how Gigaset works with Phonak but I’ve used a Panasonic cordless handset with an iPhone since March and it works pretty well. The Link2Cell connection is standard classic Bluetooth and the set is supposed to work well either with an iPhone or an Android phone. With the iPhone, a text message or call to my iPhone dings or rings on any one of the five cordless handsets scattered about the house and the name of the texter or caller is announced if they are in my phone contacts. Either by turning on Do Not Disturb or turning off Bluetooth on my phone, I can keep the handset in the bedroom from dinging or ringing when either I or my wife is asleep (haven’t looked into whether I can set Do Not Disturb for individual handsets). I’m offering this post as a general contribution to the topic of your OP “Landline Phone Bluetooth Connectivity” for the benefit of anyone interested in that topic in general. Cordless phones for the hearing-challenged. I can use a cordless phone pretty well without the sound streamed to my HA’s and even hear well enough to answer most calls when not wearing my hearing aids so my needs are less demanding than many other HA users(my linked post mentions that the handsets are T-coil-compatible but my HA’s don’t have a T-coil). We did away with our landline and the main thing the cordless handset does is give me phone receivers scattered throughout the house that run off my cell phone connected to the handset base station. Thus, I don’t have to lug a cell phone around the house with me to take a phone call ~anywhere in the house.
Hi Dont know why your Purchasing them when they are FREE as part of a Government Program,even for your Cell Phone.Your Audiologist would need to sign a Form for the Landline Phone,Its a CapTel Application and you get the phone in 2 weks,i picked (theres several models to choose from)the CapTel 2400i,which has a 8"Screen which types out the conversation from both parties,you can store it if needed.Then theres the ClearCaptions App which you download on your cell phone and a Representative will call you to set it up,your conversations are the same,dictated and you read what the other person is saying and respond,just like a normal conversation.When answering the Cell you can pick your normal way of answering it or the CapTel answering “pops up” so you can answer it that way.Its also good when doing business like myself who is a multi property owner.Ive had to refer to a conversation with a Plumber who said one thing and didnt do it and charged me for it.i referred to the conversation and was given a Partial Refund,Its a Felony to Tape a Conversation in Florida as its a 2 Party State but not with Clear Captions,your not recording it,its due to a Hearing Disability and you dont have to advise the other Party either.
Not everyone lives in the States. 
I live in Switzerland and there is no such program here that I am aware of. But your post may benefit others who have this need that you are describing.
A good idea.
I’m new to all of this so bear with me. You are using your cell phone paired with your base and handsets in the house specifically so you can answer a call with a handset no matter which room you are in if I understood you correctly.
I want to be able to connect my aids to the landline phone so I can answer the phone with my aids and have the conversation with my aids handsfree and walk around the room. (I pace a lot) I take it that this is called streaming. Thus, my question about whether an app (in my case Phonak) can control settings such as loudness and maybe tone, etc.
The Phonaks I have ordered are T-coil enabled but I have no clue yet how that works with a Bluetooth enabled cordless phone handset. I know how it works in offices, stores, airports, etc but not with phones.
Having this feature of streaming would be nice to have but it is not a deal breaker. We have to replace our cordless phones anyhow. The current ones eat rechargeable batteries as if they were regular batteries.
t-coil and bt are two separate, unrelated ways of getting the audio from the call into your HAs. One (bt) establishes a (usually) bidirectional connection and the other is much simpler, one way (into HAs) and can be as simple as the windings of an old-fashioned receiver speaker in a telephone handset driving the circuit in your HA via magnetic coupling.
best wishes on your quest
WH
But why do you want the myPhonak App to work with the landline? I think what you’re asking is impossible to do anyway.
I think it’s important to remember we are from all around the globe!
I live in the US and can’t find the Gigaset E720 for sale here, even on Amazon. I called Gigaset and they said their phones sold in the US do not connect to HAs. Does anyone know of landline phone that will connect directly to my Phonak Paradise aids, not transfer to my cell?
Like the original poster, I also want to be able to hear calls on my landline directly to my HAs. My hearing is so bad that I can barely hear on the Panasonic I bought using either the t-coil or acoustic setting.
(Sorry to highjack your post!)
You didn’t. I hope we get same suggestions.
Yet, the brochure for Gigaset states that they do connect with HAs. Hmmmmm.
Yes your right, but I gave a list of Gigaset models (don’t worry their not all just batteries)
Well this is what I was confused about, to me,it makes no sense to want to try and control your landline call through another device (your mobile phone) using the remote control functions…but I guess if you wanted to,you could use a dedicated phone program set up in your HAs, and since you have the t-coil model (this is different and not Bluetooth) you could use any landline phone (so long as it’s magnetic field was strong enough to activate the t-coil) so you have options you can try.
@jim_lewis set up is pretty cool, so another solution for you.
They said their phones can be connected to Phonak HAs elsewhere, just not the phones that are sold in the US. And the model you mentioned doesn’t seem to be available here.
Before you posted I had a support ticket into Gigaset. This is their reply:
Thank you for contacting Gigaset Technical Support.
You asked us if Gigaset E720 is compatible with the Phonak App. In regard to your request we can inform you that E720 is a standard landline home phone which is meant to be connected just directly into the phone socket and therefore it does not support any applications. The phone has Bluetooth facility which allows you to pair hearing aids with the handset.
Should you have any further questions please do not hesitate to contact us again. We would be more than glad to assist you in any way we can. For more information on Gigaset products please visit www.gigaset.com.
I’m not sure which version to believe now. I believe they do connect via bluetooth. It is just that there are no apps which allow control over volume as this support person indicated. This is from gigaset.com by the way, not Europe.
I realize that they are separate technologies. I was simply using “bluetooth” to refer to the phone I am interested in. But what I don’t know is whether this ordinary cordless phone will connect with HAs that are T-coil enabled. Does the phone have to support t-coil or are you saying that just the construction of the phone speaker is enough to connect to the t-coil. I’m sorry to ask dumb questions but I am just trying to figure out how all this technology works together.
I agree with you about this point. I didn’t think that through properly. Let me try again and maybe this won’t make any sense either but here goes. I want to connect my landline phone to my HAs (either bt or t-coil, it doesn’t matter to me) so I don’t have to use the handset. So when a call comes in on the landline phone how do I connect to the phone and answer the call through my HAs. I don’t know how to do that. Do I have to answer the phone manually, i.e., pick it up and then the voice of the person calling will be in my HAs. I thought if I could do this then I would need to have some way of controlling the volume because some people have reported that streaming from a phone can be very loud. That was the point of my question. But you are right it makes no sense to have an app on the mobile to do that.
I have telecoil on my iPhone. I have to hold my iPhone to my ear but it does stream into both my Aids. (It may not stream to both Aids as I have older Aids and DuoPhone may not be available on your Aids.)
This means, you’ll likely have to pick up the landline phone if you do go that route.
Maybe you are right, but I need to replace my landline phones anyhow, so I’ll experiment and see what happens. Thanks for the info.
Thanks for the information. I should check with Gigaset again to see if their phones sold in the US will connect to my HAs. I do know that Phonak needs HFP bluetooth protocol.
People still have land lines? 
Some of us who are “older than dirt” still have them! I also have a stereo with a turntable, cds, dvds and real books. 
Actually, I’ve had the number for 50 years. Only my friends, family and doctors get my cell phone number. And the ringer is loud enough to wake me without my HAs at night.
We have no landline. But if cable internet goes out it is a crapshoot if our phones will work. We are in a hilly rural area and signal is beyond spotty. I could see having a landline. Previous owners did.
WH
From p.63 of the owner’s manual for our Panasonic cordless handset, you can pair a BT headset with the cordless phones’ base unit - so you would have to be within BT range of the base unit to have handsfree calling. Since the base unit supports the HSP protocol, you could probably use Phonak HA’s that support BT, e.g., Marvels, Paradise, KS9’s, KS10’s, as if they were BT headsets. You can only use the headset feature with landline and it takes away one of the two possible cell phone pairings when you do:
Using a Bluetooth headset
(optional)
By pairing a Bluetooth headset to the base
unit, you can enjoy hands-free conversations
when talking on landline calls.
Important:
R Your Bluetooth headset must support the
HeadSet Profile (HSP) specification.
R Only 1 Bluetooth headset can be paired to
the base unit.
R Only 2 Bluetooth devices can be used with
the unit at the same time (for example, 2
cellular lines, or the headset and 1 cellular
line*1).
R For best performance, we recommend
using your Bluetooth headset within 1 m
(3.3 feet) of the base unit. The base unit
can communicate with Bluetooth headsets
within an approximately 10 m (33 feet).
*1 You cannot use a Bluetooth headset to
talk on a cellular line.
Link to full owner’s manual (Canadian version-can’t find U.S. version):
Operating Instructions (English) (panasonic.ca)