Hi, I forgot to mention that I had set "—ipv6” and copy/paste the code from sample. But I still got the 503 error. What else I need to do ? Thanks Qiulang /* Add TCP IPv6 transport unless it's disabled. */ if (!app_config.no_tcp app_config.ipv6) { … } Original Message Sender:qiulangqiulang@emicnet.com Recipient:pjsip listpjsip@lists.pjsip.org Date:Wednesday, Aug 3, 2016 17:13 Subject:Re: [pjsip] PJSIP version 2.5.5 is released with IPv6 support in PJNATH, DNS,and hostname resolution Hi I have used 2.5.5 in my sip client. The client is using to IPv6 and tries to connect to IPv4 sip server. I got error like16:42:27.679 tsx0x155b586a8 ..Failed to send Request msg REGISTER/cseq=6514 (tdta0x155b57600)! err=120051 (Network is unreachable) So how do I fix it? Thanks, Qiulang Original Message Sender:Mingming@teluu.com Recipient:pjsip listpjsip@lists.pjsip.org Date:Thursday, Jul 21, 2016 15:47 Subject:[pjsip] PJSIP version 2.5.5 is released with IPv6 support in PJNATH, DNS,and hostname resolution Hi all, PJSIP version 2.5.5 is just released with the main focus on: - IPv6 support in PJNATH - IPv6 support in PJLIB-UTIL DNS SRV and DNS AAAA resolution, and - IPv6 support for hostname resolution (with and without nameserver) in PJSIP and PJSUA-LIB As usual the release also includes several enhancements and bug fixes, please see the Release Notes page for more info and grab the source code from the Download page. Best regards, PJSIP team _______________________________________________ Visit our blog: http://blog.pjsip.org pjsip mailing list pjsip@lists.pjsip.org http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org