Switching between mobile network providers is easier than ever
Changing mobile networks is now much easier in many countries than switching suppliers of other regular services. Mobile number portability is fairly common, and allows you to transfer your current mobile phone number to your new provider. In some countries (e.g. Australia) this transfer can take place in a couple of hours. Others usually take a few days, but the process has been streamlined and generally works well.
Unlock codes are required where your mobile phone was originally provided under contract, usually heavily subsidised. In order to protect the subsidy, operators lock the phone so that it will only register on its network. This is done by restricting the SIM cards it will recognise to those with the operators identity (it's Mobile Network Code or MNC). My own provider will provide an unlock code when the contract period has expired for a small fee. They call this a "subsidy PIN" because it relates to the original subsidy used to buy it. There are other providers of unlock codes who will do this for a fee.
CDMA phones from networks like Sprint, Verizon Wireless in the US and Reliance in India or KDDI in Japan don't have SIM cards. The issue of unlocking the phone doesn't arise in the same way. However the handset can be sold and/or transferred for someone else to use on the same network.
Femtocells are likely to form part of your contract
Femtocells may be provided by your network operator at a price they determine, somewhere from free to cost plus. They may also charge you an ongoing fee to use it, or instead have a monthly fee relating to an additional benefit such as unlimited national calls made through it.
There may be a minimum contract period (especially if its provided free) during which the operator can recover their costs. It's still early days for femtocell commercial launches, so we don't know the full panlopy of pricing offers that will appear.
At some point, perhaps after any fixed contract period has expired, you may want to switch operators. You can unlock your handsets and insert SIM cards from another operator to achieve this quite quickly. You can transfer your mobile phone number across to the new provider in a day or two. But don't expect to be able to unlock or switch your femtocell across to a different provider. These boxes are an integral part of the operators network. They have software and compatibility with the current network operator's operations and management systems. They are unlikley to be supported by your new provider in any shape or form.
Even though there are standards for femtocells and the interfaces between key components, these are primarily to allow the operators to pick and choose between femtocell equipment providers. But I suspect that most network operators will stick to one or two femtocell suppliers and install only their management systems. They won't be able to handle femtocells from just any supplier on demand in the same way that any handset can be used on almost any network today.
But don't throw it away
In this age of greater responsibility for the environment, I'd like to think that you could either return your femtocell to the operator for use with another customer. This is similar to the process used by some Cable TV operators where their Set-Top boxes are "recycled" for use with other customers. I doubt if you would be able to sell your femtocell on eBay because the operator would have to be prepared to accept and connect it into their network, and may see this as a risk to their network integrity because they don't know where it really came from.
Femtocells are making way for the Integrated Home Gateway
A further complication is that femtocells are becoming integrated into more complex home hub boxes, which include broadband modems, IPTV, WiFi and other features. Part of the intention is of course to make it less likely you will want to switch network providers - you will be happy with all variety of services and features. It will make it a bigger change to switch than just with a single service alone.
It's all part of the business case
That of course is a part of the business case justifying the investment in a quad-play range of services which operators are promoting.
... and the answer is?
So to answer my original question - no, I don't think you will get an unlock code for your femtocell - you'll just have to send it back when you're done with it.