Hi,
This issue could very well be because of TELCO.
What I would suggest is when phone A call phone B over PSTN serviced by 2 different TELCO, make sure you are sending the proper info to your provider.
If you are sending the proper info but the called person sees the City name, its likely because the providers are not exchanging that info but overwriting it with something generic.
So, make sure you are sending the proper info and then involve your provider to troubleshoot further.
Thanks,