User A calls user B. The call gets connected, but the quality is bad. What are two reasons for this issue? (Choose two.)

An incorrect partition would prevent the call from connecting in the first place, rather than resulting in bad quality once connected.

A lack of region relationship would affect codec negotiation and bandwidth, potentially leading to no call or a different codec, but not directly causing 'bad quality' on an already connected call as definitively as congestion or incorrect QoS.

Network congestion leads to packet loss, jitter, and delay, which are primary causes of degraded voice and video call quality, manifesting as choppy audio, echoes, or dropped words.

Incorrect QoS configuration means that voice traffic is not prioritized over other network traffic. This can result in voice packets being dropped or delayed during periods of network stress, directly leading to poor call quality.

Incompatible codecs would prevent the call from connecting at all, as the endpoints would not be able to negotiate a common media format; if the call is connected, codecs are compatible.