Here's a schematic of the VCXO oscillator section from a Siemens S55 mobile phone. AFC signal coming from the processor tunes the crystal via a varicap. There's also a thermistor going back to the processor for temperature compensation. It looks like a Colpitts oscillator, but I have no idea why there are two transistors. The upper transistor base is AC-coupled to ground, which hints a cascode configuration.
Why did they choose to use such two-transistor configuration? What is the role of R955 if AC is shorted to the ground anyway - or rather why is the upper transistor base polarization connected with the signal path? What do C958 and C952 do?