NAPTR support

[pali]

Net::SIP currently does not resolve NAPTR DNS records when delivering SIP packets. NAPTR DNS records for FQDN can point to different hostnames and also contains preferences for SRV records. Therefore via NAPTR can be set preference of TCP over UDP or SIPS/TLS over SIP (unencrypted).

Also NAPTR can be used to resolve telephone number to SIP uris. So it could be used for resolving tel: URIs to SIP uris.

[noxxi]

So far I never stumbled over an actual use of NAPTR in real world, but I have limited visibility into this. Is this more an issue of feature completeness or is there an actual real world use case behind this?

[pali]

The real world use case of NAPTR is described above preference (if UDP or TCP or TLS has higher priority). E.g. if target destination prefer to use TLS over unencrypted UDP/TCP. Or if rather prefer TCP over UDP.

Other NAPTR usage (like ENUM/tel. or email) is just "feature completeness". But I have seen also NAPTR ENUM/E164 records. Some universities have their PSTN telephone numbers in ENUM DNS tree with NAPTR records and it is possible to call to these telephone numbers via internet and SIP after correctly resolving NAPTR DNS records for E164. But this is really minority.