Introduction - If you have any usage issues, please Google them yourself
Extended rewriting of PHPSIP class based on open source implements the basic functions of SIP client of php. The emphasis is on expanding support for DTMF while supporting SIPINFO mode and rfc2833 protocol. This function is not complicated, but based on the understanding of the protocol (incomplete information on the Internet), it really took me a lot of time! Because PHPSIP itself is open source, I still open my own code.