[quote=“david55”]This assumes that your correspondent accepts unauthenticated SIP calls, and either has a SIP proxy, or his phone running on the IP address associated with the DNS A record for SIPdomain.tld, or that
domain has suitable DNS records to identify the actual proxy to use.[/quote]
What’s the use of a SIP URI ?
1 contact-address where several other contact-possibilities (tel, gsm, mail) are linked in a certain sequence (user preference).
means that there should be a SIP-server (proxy) within the domain domain.tld that knows a client ‘contact’.
A DNS-query for a SIP-server in the domain domain.tld means that there must be a nameserver that has a NAPTR-record for this SIP-proxy.
The IP of this SIP-proxy will be obtained and communication will go through this SIP-proxo to his registred client ‘contact’.
Am I so wrong ?
Now, when my correspondent has a SIP-account with a VoIP-provider (who has SIP-proxies installed) then I should be able to call SIP:correspondent@VoIPprovider.tld which will redirect the call to my correspondent.
The SIP-proxy knows the IP-address of my correspondent.
So I should be able to contact my correspondent via this way, rather then call the PSTN-number.