How to fake Roaming?

[Peter Hasse]

Hi

We are planing to combine OpenBSC with our wifi mesh implementation in a 
static setup as a demo / testbed.
We would like to implement a roaming like behavior and have actually two 
approaches

1. Configuring a call forward on the phone so that it the "real" 
provider forwards the call to a number that we can route into the 
openBSC based network if the phone is not connected to its network. This 
would allow people to call "me" eager if i connected to the "real" 
network or the OpenBSC network.
Disadvantage would be that if I call somebody from the OpenBSC network 
the called party would not see the number from the "real" network.

2. Use a service like sipgate one. It would also allow a unified number 
for both "real" and OpenBSC network but if you call from the "real" 
network it has a different number.

Besides the unlikely way of real roaming with an carrier another option 
would be to fake the outgoing number. Does anybody know a service that 
could be used for that (i would need to fake a german GSM number).

Does anybody know how this is handled  on oil rigs or ships? Do they 
have a roaming agreement ?

thanks

mfg Peter