[Wellerman]

I’ve recently got a Peugeot 407sw and when I push the TEL button and nothing happens, and the same with the source button. Does anyone know why this might happen?

 

[BiGK]

Could be contact pads on the rubber membrane need cleaning.

 

[MacSlavko]

Without more data provided (a photo would help too) it's hard to say exactlly why the TEL button isn't working...
Also, it is always good to familiarize with the owner's manual...

There are two types of head units: basic radio (RD4) with a small orange screen and 3 similar types of sat-nav head units (RT3 and and RT4/5).
On RD4 it takes a whole additional box (called Nomad) to be added, plugged in the B port of the radio and configured for Handsfree cals to be available...
On the sat-nav head units it takes additional SIM card to be inserted in dedicated SIM slot of the readio. Some carriers used to offer so-called "clone SIM" or "dual SIM" subscription by which you would have the same number as the one in your mobile phone, so you'd asnwer the call (or make one) choosing one of two devices.
They used to work on 2G and 3G networks, so not really usable nowdays, but you can try it out by simply inserting the SIM card (probably needs adapter to the big SIM slot on the radio) and placing a call...

RT5 has a bulit-in Bluetooth module so it doesn't need a SIM Card as long as your mobile phone is paired with it.



As for the Source button; it'll only toggle different sources if they're available; ie. if there's no CD in the slot (or if unreadable, dusty lens etc.) or nothing attached to Aux port, the headunit will stay with the only available source (radio)...