Hi: the alleged issue you describe may not actually exist. There are no wireless components inside an OBi 200/202.
It's conceivable that placing the phone's base right on top of the OBi could flood it with enough RF interference to cause problems, but DECT 6.0 is specifically designed and internationally certified for RF safety. It operates at low power, and it has to be safe enough to hold up against your head.
You should be able to place the two units a foot or so apart, with no problem.