I have been looking for information related to the POTS signaling in use in china, but I have not been able to find much information on the public internet. It is my understanding that they are using PSTN, but I have some (possibly apochryphal) information indicating that it may vary from the system in use in North America in some meaningful way. I would greatly appreciate it if anybody here could point me in the direction of some documentation on the subject, or if you could chime in with direct knowledge, that’d be awesome too! Any pointers deeply appreciated.