Let's add small table to the readme file with the implementation status of the relevant RFCs. Those are the once I have in mind, but there might be more:

• RFC 3261 – SIP: Session Initiation Protocol (core Internet telephony signaling). datatracker.ietf

• RFC 3824 – Using E.164 Numbers with the Session Initiation Protocol (SIP) (how phone numbers map into SIP/ENUM). [datatracker.ietf](https://datatracker.ietf.org/doc/html/rfc3824)

• RFC 3966 – The tel URI for Telephone Numbers (canonical tel: URI scheme, obsoletes RFC 2806). docbox.etsi

• RFC 6116 – The E.164 to Uniform Resource Identifiers (URI) DDDS Application (ENUM) (current ENUM spec, obsoletes RFC 3761). rfc-editor

• RFC 4733 – RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals (current RTP DTMF/telephony‑event spec; obsoletes RFC 2833). datatracker.ietf

• RFC 2805 – Media Gateway Control Protocol (MGCP) Architecture and Requirements. tools.wordtothewise

• RFC 3435 – Media Gateway Control Protocol (MGCP) Version 1.0 (MGCP call‑agent ↔ gateway control). hjp

• RFC 3660 – Basic Media Gateway Control Protocol (MGCP) Packages. datatracker.ietf

• RFC 3661 – Media Gateway Control Protocol (MGCP) Return Code Usage. rfc-editor

• RFC 3991 – MGCP Redirect and Reset Package. ftp.ripe

• RFC 6230 – Media Control Channel Framework (SIP‑based framework to control external media servers for conferencing/IVR). faqs

• RFC 6231 – An Interactive Voice Response (IVR) Control Package for the Media Control Channel Framework. faqs

• RFC 4458 – SIP URIs for Applications such as Voicemail and IVR. [datatracker.ietf](https://datatracker.ietf.org/doc/html/rfc4458)

• RFC 3880 – Call Processing Language (CPL): A Language for User Control of Internet Telephony Services. rfc-editor

• RFC 3801 – Voice Profile for Internet Mail – version 2 (VPIMv2) (voice mail over Internet mail between voice servers). [datatracker.ietf](https://datatracker.ietf.org/doc/rfc3801/)

• RFC 4239 – Internet Voice Messaging (IVM) (standardized Internet voice‑message format). [datatracker.ietf](https://datatracker.ietf.org/doc/html/rfc4239)

• RFC 2871 – A Framework for Telephony Routing over IP. [datatracker.ietf](https://datatracker.ietf.org/doc/html/rfc2871)

• RFC 3219 – Telephony Routing over IP (TRIP) (inter‑domain routing of telephony destinations). datatracker.ietf

• RFC 5115 – Telephony Routing over IP (TRIP) Attribute for Resource Priority (priority services over TRIP). potaroo