Google Voice is an online call forwarding service that gives you an American phone number that can be linked to all your other phone services. The idea is that this number will follow you around. You can use Google Voice a voicemail dropoff and transcription service or as a switchboard to forward your calls to your other numbers. It is similar to Skype and other VOIP services inasmuch as you can use Google Voice to make cheaper calls to landlines and cellphones in the US and internationally.

SkypeIn is not available in China, but I will show you how to create a local number for all your contacts using Rebtel's collect call option. This means that my family in the UK can call a local number, which is routed to a Chinese number. This also means that I pay for people to call me from the UK, but it also means that you only get calls from your Rebtel contact list. I'm going to go one step further and route calls from China or the UK to Skype via Google Voice.

There are a few sticking points to getting Google Voice to work in China:

1. You need an invitation to join Google Voice. It is not open to everyone.
2. You need to have an American IP address to setup Google Voice. It is only open to people in the US.
3. You need to use American telephone numbers to link to your Google Voice number.
4. Your contacts need to dial an American telephone to call you on Google Voice.

How do we get beyond these deal breakers? I have summarised the basic workflow rather than providing a granular step by step tutorial. I'm happy to do this at a later stage if there is a need and a wish.

1. Get a Google Voice Inviation
   Google Voice invitations are easier to track down now. Ask for one on Twitter or look around for a site like Inviteshare.com
2. Get a US IP address
   I used a private paid for VPN (StrongVPN.com) to get a US IP address.
3. Get a US phone number, which you link to Google Voice
   I got a free US landline number, which I found by signing up to IPKall.com. I used it to link my SIPPhone account on Gizmo5 to a US landline number. Gizmo5 is an alternative to Skype that lets you make cheap phonecalls from your computer or cellphone using a Java mobile client. Google just bought Gizmo5 so it is no longer available to newcomers, but there maybe SIP alternatives if you get stuck. I used my IPKall US landline number to receive and forward calls via Google Voice.
4. Route locals from a local number to your Google Voice account
   Get a Rebtel account, which allows your contacts to make collect calls to your international phone services using a local number. Each call can be routed to your SIPPhone or IPKall number via Google Voice. It is also possible to forward calls from Gizmo5 to Skype or Google Talk .
   

This strange hack means I can use a data only China Unicom 3G sim card on a smartphone that runs Skype or a SIPPhone client. A blended voice and data plan is expensive costing 386 RMB for 1.3 GB a month, whereas you pay 200 RMB for 5GB using a data only 3G package over the same period. In effect you are using VOIP via 3G and wifi to replace China Unicom for voice calls. This is great for people like me who like to use their cellphones to access the Internet and run applications rather than making telephone calls. I have not yet got this to work on a Smartphone. I will post an update when I try making data only calls on my new Nexus One, which arrives from the UK next week.

I have got this solution to work quite well using an Ubuntu netbook running Skype through a USB 3G dongle. There is a caveat, however. The convoluted routing of calls caused a slight delay and I had to get Skype to automatically answer when receiving calls via Google Voice. I intend to keep a VPN switched on when using my phone to make VOIP calls. I am sure China Unicom prefers customers to pay for regular and more expensive cellphone minutes given SkypeIn is not permitted in China. I hope China Unicom will not find a way to break my workaround.