Forwarding SIP Calls to Google Voice

Warning/Disclaimer: This information is based on unsupported features of Google Voice and as such may change or be blocked at any time. Don’t rely on it for important communication needs.

Ok, having said that, let’s talk about the ability to forward SIP calls to your Google Voice number via a direct SIP-to-SIP connection which in turn are forwarded by Google to your registered phones.

This is a cool feature for people who already use SIP based phones because it extends the receiving end of the connection to your mobile and landline phones. The list of potential uses and benefits is pretty long and I’ll spare you from having to read through a regurgitated list of them from me.

To make this as simple as possible and leave you some flexibility in the configuration side should it need to change, you’re going to want two Gizmo accounts. This is assuming you want the ability to receive calls via SIP as well (see my previous blog post on how to set up Gizmo/X-Lite with Google Voice).

This post just concerned with the Gizmo Forwarding Account highlighted in the diagram above.

If you already have a Gizmo account and you’ve shared that SIP number with others, you’ll want to create a new account to use as your Gizmo Receiving Account and use your existing one as the Gizmo Forwarding Account. That way you won’t have to give out a new number.

Before you can configure your Gizmo account to forward calls, you need to know your Google Voice SIP address. And herein lies the tricky part. The Google Voice connection to Gizmo is a two-way capable connection but they don’t give you any information on how to receive calls via that connection. Why not? The list of reasons that people have suggested could fill a blog post by themselves. My feelings are that since Google Voice (and Grand Central before it) haven’t blocked incoming calls, they condone it’s use, but just can’t commit to supporting it so they don’t mention it. A quick search of the internet shows that this inbound connection has existed for a long time and they would have closed it by now if they wanted it closed. So for now, we’ll make use of it.

Here’s the format of the Google Voice SIP address:

6305551234@216.239.37.11:5061

The first part is your Google Voice phone number followed by the @ symbol then a Google Voice server IP address and then a colon and port number. This number is the from address that is passed to Gizmo/X-Lite when a call comes in from Google Voice. The “.11” portion of the IP address changes from time to time and is sometime “.14” or “.15” among others. I suggest trying “.11” for now and if that fails you can try “.14” or “.15”.

With your Google Voice SIP address in hand, setting up a Gizmo account to forward is really easy. Here’s a screenshot.

In the Forwarding Gizmo5 Calls section of your account page, set the status to “Forwarding All Calls” and then set the ID radio button to SIP and enter your Google Voice SIP address and hit save. You can also turn off the Gizmo voicemail while you’re here if it’s active.

That’s literally all there is to it. You can now have people call your Gizmo Forwarding Account’s SIP number and they’ll be automatically forwarded to your Google Voice number which will ring your phones.

The beauty here is you have a number that you can give out and if things stop working you still have options. You can fix the forwarding number if it changes, or you can forward directly to your Gizmo Receiving Account.

Since all the technology is in place for this to work quite seamlessly, I really hope the Google Voice powers that be make this an official feature. If it get’s turned off at some point it will likely be due to some sort of legal, regulatory or outside business pressure.

The world’s changing and Google Voice is leading the way. I hope it’s allowed to continue.

Note: Should things change with this “feature”, I’ll update this post.