Yes, for SIPp load testing with INVITEs and RTP, you absolutely need an XML scenario file. The `uac_pcap.xml` or `uac.xml` are good starting points that you'd then customize with your SBC's details and SDP for RTP.

**Tip:** If writing/editing SIPp XML gets tedious, you might find a GUI tool helpful. My open-source project, **kSipP**, provides a web-based interface to build and run SIPp scenarios visually, including an [online SIPp XML generator](https://kiran-daware.github.io/sipp-xml/). Check out (https://github.com/kiran-daware/kSipP)