Is the gadget in the pic something that will give me Bluetooth connectivity for calls? Bit confused, as some places refer to it as a 'Bluetooth adapter', some say it takes a SIM card and acts as a phone itself, rather than hooking up to a separate handset.
It is a Mercedes OEM Bluetooth adapter, similar to the Viseeo aftermarket models.
They sit in the telephone cradle designed for Nokia type phones and enable hands-free bluetooth connectivity via the Headunit with a smartphone. No SIM Card capability. It connects your phone to the car.
Looks to me like the car had the UHI connector for various phone cradle models. Early W211 cars did not have UHI yet but had it from 2004/2005 onwards. Thought the CLS would have UHI from start of production.
The OEM Mercedes bluetooth adapter does not sit in the Nokia cradle but is attached to the UHI connector, replacing a phone model specific cradle.
This adapter looks like the bluetooth SAP variant (Mercedes part number under the adapter would tell for sure) which has a SIM car slot. It operates as a normal phone if SIM is inserted. If not, it works via bluetooth but using BT SAP profile which all phones do not support (like iPhone).
The "European" BT HF profile adapter was black, the US model looked like the one on the photo here. So better check the part number.
ViseeO had a product with Nokia 6310i like shape and connector that was inserted to a Nokia 63101 cradle (or the phone adapter before UHI). ViseeO later on had another adapter that fits directly to the UHI adapter like the MB adapter does.