PJSIP is the emerging SIP technology in Asterisk. It provides additional functionality and features not present in the legacy chan_sip and over time it will become the predominant SIP technology. However, because of it's youth and more extensive feature set, customers are likely to encounter more bugs and issues. We encourage customer who either need these features or want to help progress and mature the technology to run with PJSIP, even in production, with the acknowledgement that there will be more issues. The Asterisk and FreePBX (Sangoma) Development teams are fully behind PJSIP and will try to address all bugs and issues that arise from it. However, chan_sip still remains the mature SIP channel that should be used where stability is the most critical factor and tolerance for early adoption of new technologies can't be tolerated.