What types of SIP endpoints can connect to 3CX?

3CX supports a variety of SIP endpoints that can connect to its system. VoIP phones and PSTN gateways are two key components of this ecosystem. VoIP phones utilize the SIP protocol to communicate over the internet, allowing for features like call transfer, voicemail, and conferencing, all integral to modern telephony solutions. PSTN gateways, on the other hand, bridge traditional analog telephony systems with VoIP networks, enabling seamless integration of legacy systems.

Other options such as analog phones, cell phones, and standard telephones generally do not directly support SIP without additional hardware or configuration. Analog phones require an adapter to convert their signals into a digital format that SIP systems can understand, while cell phones typically connect via mobile networks rather than being native SIP endpoints. Standard telephones, akin to analog phones, need an interface to connect to SIP-based platforms. This versatility and compatibility with robust SIP technology make the combination of VoIP phones and PSTN gateways the correct answer to the question.