With the Oticon Streamer (and possibly the Phonak iCom but I don’t know for sure)…
There are actually 2 kinds of T-Coils in the Oticon Epoq. One is a standard T-Coil and that is what is used for the old fashioned phone setting (T or M&T program). It can be triggered by the Auto Phone switch which is a magnetic reed switch. It can also be triggered by a manual phone program. Which you turn on/off by changing to program 2,3 or 4 with a button push…
I was told that the T-Coil(s) in the HAs used by the Streamer are digital and are “paired” to your Streamer by the AuD when he/she sets you up. (They have to put in the Serial Number of the HAs to match to your streamer i think)
As far as I know, the Phonak iCom & Oticon Streamer and Siemens Unit are all connecting to proprietary T-Coils or possibly FM in the HAs. ie. You could not use an iCom with an Epoq HA.
The 3rd party BT & Loop devices would be connecting to the Standard type T-Coils via a personal loop system. Basically the same way they would connect to a room loop.
The only part of any of the systems, propietary or 3rd Party, that uses Bluetooth is the connection between the Streamer and the Source Device ie. phone, iPod, TV Transmitter or CPU which must have bluetooth also.
If you & spouse have different HAs, you could probably use a room loop or there is also a number of TV listeing devices that work with a neck loop & the Standard T-Coil. Many have independant neck loops and many also have a cord that can be plugged into a Streamer or iCom audio input jack. So you & wife could use the same unit.