For many developers, the "FreeSWITCH 1.8 PDF" refers to the highly regarded book FreeSWITCH 1.8
Version 1.8 solidified the inline dialplan. Your PDF will detail: freeswitch 18 pdf
That said, if you need AV1 video codecs or full QUIC support, you must upgrade. But for 90% of standard business VoIP needs (SIP trunks, queues, IVR, recording), FreeSWITCH 1.8 is still rock solid. For many developers, the "FreeSWITCH 1