I had a 8851 phone at work (University with a Cisco VOIP system). I have no experience with Phonak aids or Roger but I was able to use my Oticon OPN S 1 aids with a ConnectClip with the 8851. In my case, I was able to pair the phone with the ConnectClip which was paired with the aids. The combination became a headset for the phone where the directional microphone in the ConnectClip picked up my voice and the aids were the headphone part of the “headset”. The ConnectClip (Bluetooth 4.2 + EDR) operated fine with the older Bluetooth 3 of the phone. The ConnectClip has a button to answer the phone. Even though the ConnectClip is supposed to be optimized for voice pickup when worn appropriately, some people noticed excessive room noise with my voice (loud AC fans in my office).
The typical problems with this type of setup are the limited range due to low power bluetooth, typically Class 2, and poor pickup of the voice by the hearing aid microphones if they are used rather than a more optimally placed microphone such as one on a “boom” near your lips and possibly with noise reduction.
The following are only suggestions of things to consider - others probably have better suggestions, expertise, or experience.
There are Class 1 bluetooth devices that can have higher transmitted power (up to 100 milliWatts vs the typical 2.5 milliWatts of a Class 2 device) with a possible longer range (up to 50 meters or so as compared to 5 to maybe 10). The range may be MUCH shorter for either class with obstructions that block or strongly attenuate the 2.5 GHz Bluetooth signal. I don’t know if the Cisco phone might accept a USB Bluetooth dongle that is Class 1 (for example the BTD 800 one that was supplied with my ConnectClip). I use the BTD 800 with a Mac at home and it provides fairly long range including through some walls. I no longer have the 8851 phone as the University has switched phone systems to Zoom phone so I can’t test if the BTD 800 works in the USB port of the 8851. There are other dongles that are also Class 1 that may have later versions of Bluetooth.
The document from phonakpro that rothlev1 posted seems to show a Roger Select as their solution to connecting to call system phone systems. However the Select is only a Class 2 device with short range although it might do a better job of transmitting your voice than the hearing aid microphones.
I might be tempted to try a high-end Bluetooth headset with large closed ear cups that would provide passive noise reduction by sealing against your head, especially if they had a “transparency” mode. I’ve been able to use large cup closed headphones with my aids without feedback. The headset would have Bluetooth - some might be available with Class 1 bluetooth as they can have much larger batteries than hearing aids. You would use the headset bluetooth rather than the hearing aid bluetooth. That way your voice would probably be less muffled since you are using a headset microphone optimized for voice pickup and possibly noise reduction. Some Plantronics headset control devices used to work with Bluetooth dongles - you would plug such a control device into the headset port of the 8851 to use the dongle Bluetooth instead of the built-in bluetooth. There are probably other vendors but I knew someone who used a Plantronics switching device. If the dongle were Class 1 and the headset were also, then you might have adequate range for your needs.
Good luck finding a usable solution.
