Thats definitely a bit off-topic from the regular Server product posts that I have.
However, I found it to be an interesting topic as not many guys here in India are familiar with what is - Number Portability.
Mobile Number Portability (MNP) actually refers to the arrangement between the mobile service providers that allows the customers to retain their own number even when they switch the providers. The Regional Telecom Regulatory Authority of course needs to have a rule in place for the MNP to take effect.
Each mobile service provider has his own set of numbers that are approved by the regional TRA. This is normally a series that is different for each mobile operator. For example in the Maharashtra state, BPL Mobile numbers start with 9823, however, the AT&T numbers start with 9822. So they follow their respective series. If a customer needs to change from BPL to AT&T, then he has to change the number and choose from one of the numbers available with AT&T.
With number portability, the customer can still keep his old BPL number in place and can avail the facilities of the AT&T network. So whereas the billing and network provisioning goes to AT&T, the customer still uses his original BPL number.
This arragement is quite uncommon in India. In fact, none of the Indian regional TRAs support Number Portability. Much of it is attributed to the number of service providers and the competition in the region. However, this is more common in other countries where these scenarios do not exists.
Lastly, to link this up with some techie stuff, a number portability solution would form a perfect fit for a sizable Biztalk project. Much due to its various workflows, rules imposed by the TRA and obviously because it involves integrating the two service providers systems 🙂