Just as a warning to anyone who might try this, it won't work. (At least not without a massive amount of opsec effort expended on your side.)
I'll give you an example of why it might not work. Since your phone has roaming, you happen to have it with you at work, or at a party, or at the library, or anywhere really. If even a single acquaintance of yours is "nearby", the information is leaked. If acquaintances seem to always be "nearby", children, wives, husbands, siblings, your info is DEFINITELY leaked.
If anyone is going to try to use this strategy for anything which might result in the loss of your livelihood, (eg - porn), please realize there are many, many, many more precautions you will have to take than are listed in oedfmarap's comment. If you just do what you see in that comment, you could find yourself without a job somewhere down the line.
While one would think that this is only important for things you're doing that you don't want the government to know about (see [1] page 52 for details on how not to mess this up -- basically don't have them turned on together, don't turn one off and turn the other on in the same place, or log in to the same sites or store the same numbers on both phones), it's also important for Facebook and other private tracking. If you have Facebook on your burner phone and your friends have Facebook on their phones with location enabled, it's over [2].
I'll give you an example of why it might not work. Since your phone has roaming, you happen to have it with you at work, or at a party, or at the library, or anywhere really. If even a single acquaintance of yours is "nearby", the information is leaked. If acquaintances seem to always be "nearby", children, wives, husbands, siblings, your info is DEFINITELY leaked.
If anyone is going to try to use this strategy for anything which might result in the loss of your livelihood, (eg - porn), please realize there are many, many, many more precautions you will have to take than are listed in oedfmarap's comment. If you just do what you see in that comment, you could find yourself without a job somewhere down the line.