Answer

Yes, in our D3XX and D7XX series phones jitter buffer is adaptive.

It is possible to see the jitter buffer values for every call by enabling the RTCP-XR reports.

Example:

JitterBuffer:JBA=3 JBR=2 JBN=40 JBM=40 JBX=240

From https://tools.ietf.org/html/rfc3611#section-4.7.7 :

• JBA = AdaptiveJBR = JB adjustment rate
• JBN = JB Nominal
• JBM = JB MAX
• JBX = JB Absolute MAX