- Whenever our users make a call, their phone does two checks:
- ENUM lookup on the dialed phone number, using e164.arpa, e164-addr.sip5060.net and e164.org. If a SIP address is found, Lumicall will send that SIP address to the proxy.
- If a contact from the address book has been dialed, Lumicall scans each email address for the contact. If a DNS SRV record for SIP exists for the domain, with TLS support (_sips._tcp), then the email address is treated as a SIP address and the user will be given the option to call this address.
- When the call hits our SIP proxy, the router will repeat the DNS SRV lookup, and look for a TLS entry
- Our router will try to connect using TLS
We recommend that you make sure you have both ENUM registrations for your phone numbers and DNS SRV records for your email domains: this will maximise the probability that calls can be routed to you.
For both calling our users and receiving calls from our users, it is important that a common set of codecs is used - see our Codec recommendations
Example - Alice calling Bob
- Alice dials Bob's number
- Lumicall detects that Bob is in Alice's contact list
- Lumicall also finds Bob's email addresses, email@example.com and firstname.lastname@example.org in Alice's contact list
- Lumicall performs a DNS SRV query on _sips._tcp.example.com and _sips._tcp.example.org - but it only receives a response for the latter
- Lumicall performs an ENUM lookup on Bob's phone number, and finds a SIP address email@example.com
- Therefore, Lumicall concludes that it can try both sip:firstname.lastname@example.org and sip:email@example.com. It offers these choices to Alice.