Sorry, to be the bearer of bad news, but is all likelhood, you're not going to get your phone back.
Are you certain it was stolen, as in you caught someone pickpocketing you? If there's a chance that it may have been dropped on the ground and someone finds it, the most you can hope is that someone brings it into a police station as lost property.
If the phone was misplaced, suspending the service and locking out the phone would prevent someone from figuring out how to contact you to try to return it.
Personally, I would not keep the service active for any reason if you don't know where the phone is. The last thing you want is someone using the phone for potentially illegal purposes and having the police start questioning you when you'v done nothing wrong.
As for wanting to keep data active so you can locate the phone, even if you locate it, what are you going to do? If the phone is truly stolen, it is proabably very unwise to confront someone with possible connections to the criminal elements.
As mentioned earlier, my advice would also be to move on, blacklist the device, and passcode lock it so that no one can use that device (although they could still use the parts in it).
