DNS SRV+NAPTR vs. ENUM?

[voip247]

After investigating ENUM, I'm starting to think that the "your email address is the only address you need" idea advocated by http://internet2.edu/sip.edu may be a better idea than ENUM. With official (e164.arpa) ENUM, the DID provider apparently decides whether or not you will get an ENUM entry. Both sipgate.de (sipgate.co.uk) and FWD used to issue ENUM entries, but both appear to be abandoning user ENUM (e164.arpa and e164.org) for carrier ENUM (e164.info). (FWD's ENUM entries are still in e164.org, but not in e164.arpa. Also, I checked a recent 49 DID number from sipgate and it is not listed in e164.org, e164.arpa, or even e164.info.)

I think the general idea of DNS SRV and/or NAPTR records is that you could right-click on an email address on a web page, choose "call", and then your softphone would look up the SIP address from the email address and make the call. For example, pulver.communicator softphone accepts cut&paste email addresses from http://internet2.edu/sip.edu (sip:mark@mit.edu goes to his voicemail). Also, Sipura adapters have "DNS SRV Auto Prefix", so maybe all that's needed is for users like me to:
1) Get a domain name.
2) Make granitecanyon.com my domain's DNS server.
3) Enter my SIP address in the SRV and/or NAPTR record for my email address.
4) Give out sip:myname@mydomain.com as my permanent Internet phone number.
5) People who want to call me would paste my email address into a softphone (like pulver.communicator) or into the speed-dial web page of a hardware adapter (like Sipura) or use a "click-to-call SIP address book" web site (I don't know of any).

Does anyone know if this would work? If so, can you list the *specific* steps of one or two concrete examples? (Does granitecanyon even permit these types of DNS records?? Can I use Windows' nslookup command to check SRV and NAPTR records?) I suppose the RFCs would explain it in an abstract/non-VoIP way, but they probably would not give even a single reproducible working example.

Of course, ENUM has the advantage of being dialable from touch tone PSTN phones, but if DID providers choose not to give users corresponding ENUM entries (even for DIDs in European countries that have already implemented official ENUM), then users won't get ENUM at all. And DID providers are probably waiting for ENUM to become popular, which will never happen if users can't set it up on their own. Also, phone-by-number has the disadvantages of misdialing, constant mandatory area code changes, international access codes that vary by country (011, 00, 01), etc. Most VoIP users are probably already sitting in front of the computer anyway, so one click to call by email address might just be easier than punching 7-18 digits into a touch tone phone.

NAPTR SRV_record Electronic_Numbering

[mberlant]

Your take on the problem is encouraging - until I read your last paragraph.

Of course, ENUM has the advantage of being dialable from touch tone PSTN phones, but if DID providers choose not to give users corresponding ENUM entries (even for DIDs in European countries that have already implemented official ENUM), then users won't get ENUM at all. And DID providers are probably waiting for ENUM to become popular, which will never happen if users can't set it up on their own. Also, phone-by-number has the disadvantages of misdialing, constant mandatory area code changes, international access codes that vary by country (011, 00, 01), etc. Most VoIP users are probably already sitting in front of the computer anyway, so one click to call by email address might just be easier than punching 7-18 digits into a touch tone phone.

Phone by number has the distinct advantage of being dialable from an ordinary phone. I believe that most VoIP users are not sitting in front of a computer, nor do they want to clutter the screen with an IM-like interface just for VoIP. Also, if the user is in front of the computer when he wants to make a call it is rather intrusive to put the computer work on hold to bring up the CTI window in order to make a telephone call.

Fully 100% of the VoIP users I deal with regularly use an ATA with more than one ordinary telephones connected to it as their primary VoIP access environment. Some of these people also keep a copy of X-Lite or SJPhone on a laptop for occasions when carrying a small ATA is either inconvenient or inappropriate. I don't see these people, for whom a telephone is always at hand, walking over to a computer just to see if a particular person has a VoIP-enabled email address.

Additionally, shifting VoIP from being numeric (PSTN-like) to alpha (email-like) is tantamount to forcing VoIP into the instant messaging realm, as I see it. Many of us remember the first incarnation of FWD and Dialpad and also remember our happiness watching these two pioneering companies evolve into the real SIP services they are today.

In fact, as I sit here typing I wonder just how you envision this CTI functioning. When you are sitting in the kitchen and want to call me, for example, how will you get your CTI to click-and-dial me without disturbing everyone else in the house by ringing their extensions? I suppose if you have an ATA that supports Distinctive Ring you can have this CTI "callback" ring on a different cadence so that only the person who originated the call will pick up the phone.

By the way, it is just as easy to avoid misdials by storing numbers in Speed Dial - just as easy as storing email addresses in a click-and-dial directory. Conversely, it is just as easy to mistype an email address as to misdial a telephone number. That makes me call this argument a wash.