# Features and Limitations

NbUP endpoint supports the following features related to NbUP protocol:

- Supports outbound (Master mode) as well as inbound (Slave mode) Iu UP INIT procedure.

- Supports PDU type 0 (with payload CRC) as well as PDU type 1 (without payload CRC) for transfer of user data.

- Supported media types include:

- - G.711/PCM – Supports 5 ms packetization and 20 ms packetization.

  - AMR – All data rates supported by Fusion are supported. (20 ms packetization time)

  - H.223 – Both 5 ms packetization and 20 ms packetization are supported.

- Frame numbering based on sent Iu UP PDU is supported. Frame numbering based on Time is not supported.

- The transport layer for Nb UP shall be RTP/IPv4. IPv6 is not supported.