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Google Dips Its Toes in the Icy SIP Waters… and Retreats

In case you missed it, Google announced at the end of last week that it will discontinue support of Gizmo5 on April 3. Many of us suspected this was the death knell for Google support of SIP given the popularity of its recent Gtalk enhancements to Google Voice. Well, not so fast! As Todd Vierling pointed out on his blog this past Saturday, Google has quietly added outbound SIP support to reach any Google Voice number. So, assuming your Google Voice number is 678-123-4567, anyone in the world can now call you via SIP by dialing +16781234567@sip.voice.google.com.

For those using Asterisk® and FreeSwitch systems , here’s what you need to do immediately. Register all of your Google Voice numbers in the ENUM systems so that other Asterisk and FreeSwitch systems worldwide can connect with you using your new Google SIP URI without any communications charges. This also means that SIP phones such as the Nortel 1535 Color Videophone using services such as sip2sip.info can call you for free. And all they’ll need to do is dial your 10-digit Google Voice number!

To sign up for ENUM service, go to both e164.org and enumplus.org and register your 10-digit Google Voice number. Be sure to use the syntax shown above for the SIP URI (including the + symbol), or the calls will fail. It only takes a minute to register. ENUM is implemented for outbound calls by default in all Incredible PBX and Orgasmatron builds. So, just by registering your Google Voice number with these two sites, it means every ENUM-enabled server can place free SIP calls to your Google Voice number via ENUM before using any other outbound trunk for which there might be a charge.

Of course, everyone won’t register their Google Voice number with the ENUM services. So how do you call those folks via SIP without incurring charges for the call? For those that install Incredible PBX (beginning yesterday), it’s automagic. Just dial any 10-digit number, and Incredible PBX will attempt to place the call via SIP before falling back to Google Voice. The call processing is instantaneous so don’t worry about call delay. Remember, we’re living in a Digital World.

FreePBX Setup. If you have an existing FreePBX-based Asterisk system or an earlier release of Incredible PBX, here’s how to retrofit your system to support free SIP calling to Google Voice numbers. Whenever an Asterisk server attempts to place a SIP call, it sends a SIP Invite packet to the receiving server. In the case of Google, if the number is not one of theirs, you’ll immediately get a Congestion message from FreePBX. In the FreePBX design, this means that the attempt to place the outbound call will drop down to the next available trunk in the current Outbound Route. So the trick here is to create a custom trunk to handle the SIP calls to Google. And then we’ll add that trunk above your existing trunks in the Outbound Route that handles calls matching 1NXXNXXXXXX and NXXNXXXXXX. So the recommended Trunk Sequence in your Default Outbound Route would look like this:

2. google-sip
3. gvoice
4. vitel-outbound
5. OtherProvider

Using a web browser, open FreePBX and choose Setup, Trunks, Add Custom Trunk. Create the new Google-SIP Trunk so that it looks like the following. Don’t forget the 1 Prepend and + Dial Prefix entries!

Click Submit Changes to save your entries and then reload FreePBX when prompted.

Now choose Setup, Outbound Routes, and choose your Default outbound route. Modify the Trunk Sequence so that it matches what was outlined above. Click Submit Changes to save your entries and then reload FreePBX when prompted.

You’re done. Enjoy your new SIP-based Google Voice calling addition.

Don’t forget to List Yourself in Directory Assistance so everyone can find you by dialing 411. And add your new number to the Do Not Call Registry to block telemarketing calls. Or just call 888-382-1222 from your new Google Voice number. Enjoy!


March 8 Update. Well, that was a quick dip. Beware the Ides of March! It was almost exactly two years ago that Google shut down SIP connectivity the first time. Hopefully, we’re not in for another two year wait. Read our original article about this and have a chuckle. But it looks like they’ve done it again. To restore your system to normal functionality, remove the Google-SIP trunk from your Outbound Route and be sure to delete your Google Voice numbers from the SIP registries at e164.org and enumplus.org. To suggest this is short-sighted (not to mention monetarily wasteful) would be an understatement. But perhaps Google wasn’t prepared for the onslaught of delighted users. Let’s hope so. 🙄

March 16 Update. It’s working again this morning! But now it’s not morning, and we’re dead in the water once more. Did we mention this might qualify as E-X-P-E-R-I-M-E-N-T-A-L?? See the comments below for up-to-the-minute updates.

Security Reminder. We mentioned this two years ago, but it’s worth repeating since it still has not been addressed. Google protects phone access to your Google Voice account with only a 4-digit PIN. When unanswered calls roll over to their voicemail system, anyone has the option of pressing * to be prompted for this PIN. It only takes 10,000 calls at most to guess any PIN, and that doesn’t take very long with SIP and an automated dialer. Once someone has your PIN, in addition to listening to your voicmail messages, they also can press 2 to place an outbound call to anywhere in the world… on your nickel. So… don’t load up your account with your entire life savings unless you don’t mind losing it. 🙄

Originally published: Monday, March 7, 2011

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  1. This is good news! Does this mean Google looses termination revenues for all its DIDs?

    Also, SIPifying in one direction SIP=>GV; but not in the other – GV=>SIP.

    I have heard rumors that GV will support SIP for callback on Android 3.0(?).

  2. So this change is only for incoming calls on Google Voice, right?
    As in, it’s not a new way of dialing out from GV, only a new way to reach a GV number?

    [WM: It’s a little of both. SIP support adds a new way to receive incoming calls to your Google Voice numbers. And, for those using SIP phones or SIP-based PBXs such as Asterisk or FreeSwitch, it provides a new way to place outbound calls to Google Voice numbers at no cost.]

  3. Okay now I’m confused… Wasn’t Google already offering free calls to US & CAN numbers for 2011? So this new change of procedures, is it a benefit directed at international callers? For US & CAN callers, is this change significant?

    [WM: Google Voice calling via Gtalk still works as advertised. The SIP addition simply provides another (free) way to make calls to Google Voice numbers. And it works worldwide. Finally, if Google does ever start charging for calls, this will provide a way to continue to reach Google Voice numbers at no cost. ]

  4. The 1NXXNXXXXXX rule is unnecessary – it’s not adding a digit, stripping a digit, or being used as a "stopper" so that a subsequent rule is ignored, therefore it’s extraneous Remember that trunk rules are only used for changing the called number in some way, and serve a quite different purpose from outbound route rules, even though you can now add or strip digits in both places.

    [WM: This depends upon how your Outbound Routes and other Trunks are set up. Calls start at the Outbound Route with a matching Dial String and then proceed down through the designated Trunks in sequence. To have a match on a Trunk, you have to have a Dial String entry for the Trunk that matches what was passed from the Outbound Route. Keep in mind that our articles are written to accommodate system designs of thousands of different Asterisk users. So what you or I would do is secondary to assuring that something "just works" for everybody. Without getting too deep in the weeds, it’s worth noting that it is not uncommon to see an Outbound Route with only two dial string entries: 1NXXNXXXXXX and NXXNXXXXXX. With such a setup, the 1 does need to be added as a prepend in the Google-SIP Trunk, or calls dialed as 10-digit numbers would always fail when the call hit the Google-SIP trunk without the 1+NXXNXXXXXX entry. And, for anyone that dials an 11-digit number, the 1NXXNXXXXXX entry catches that type of call. You are correct that the rule is redundant with FreePBX 2.8; however, not everyone is quite there yet. There is no single "right way" which, of course, is one of the beauties of Asterisk and FreePBX. Our design was intended to eliminate as many "wrong ways" as possible.]

  5. Thanks for the info.
    So is there anything else I have to do to my system to receive incoming calls to my Google Voice number over SIP? Or is that in there automatically on Google’s end?

    [WM: It’s automagic on Google’s end.]

  6. Well, I tried this on two different systems that are running FreePBX and Asterisk. On one, an Asterisk 1.4/FreePBX 2.7 system, it seemed to work fine earlier today, but now it seems that there is about a 30 second delay before ANY response is returned. That means that if I call a Google Voice number, it takes 30 seconds for it to start ringing, and if it’s a non-GV number, it takes 30 seconds to return a response so FreePBX will fall through to another trunk. This just started this evening; earlier today it worked flawlessly.

    On the other hand, on an Asterik 1.8/FreePBX 2.8 based system, if the call was not to a GV number it would not fall through to another trunk. The weird part was that I watched the CLI and it SAID it was falling through to another trunk, it just wouldn’t actually DO it. Calls to Google Voice going out the normal way (using the Asterisk 1.8 channel drivers) work fine, as do calls using the above method when made to a Google Voice number, but when I tried calling a non-GV number it just wouldn’t fall through to the next trunk (and I even tried adding the useless 1NXXNXXXXXX pattern, though I know it has no effect — I guess we’ll just have to agree to disagree on that one, Ward).

    Anyway, I’d be a little careful about doing this on any production system. I wasn’t going to say anything about the problem on the second system but when the 30 second delay appeared out of nowhere (and disappeared after I disabled the custom trunk), I figured maybe I should let you guys know, so you can at least make sure it’s not happening on your systems.

  7. Yes, I had it working this morning from Blink and Tropo flawlessly, now it simply does not work no matter what I try.

    Has Google shut this down already?

    [WM: Yep. It’s dead for us, too, but still works for a precious few. That was fun.]

  8. See. This is why I wait a few days before implementing anything involving Google. Their "test labs" are always going up and down. If something stays working for a few weeks, then I look into it.

    [WM: True, but without the Pioneers, where would we all be?]

  9. Ward, Kind of curious, e164.org states you have to use an ISP email address. That kind of shots the gmail email address in the foot. Has anyone
    tried the gmail email address when registering?

    Just curious.

  10. Thanks again for another great article.

    I was wondering about the e164.org registration for my GV number. I followed the directions using the +1 in front of my 10D GV number but e164.org doesn’t like something.

    Here is the error:
    Wasn’t able to test your route, your system returned the following information: -1|Error 504 – No response was returned from the remote end, this might indicate a problem with a firewall connection

    The enumplus.org went great. No troubles.

    Any thoughts?

    [WM: Probably the result of Google shutting down the SIP service again. 🙄 ]

  11. Worked when I tried again so must have been a Google hiccup. Dang them and their free services! 😉

    Thanks again,

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