Using pbxes.org as my SIP provider, telepathy-sofiasip fails to connect because it attempts an SCTP connection and I don't have support for that built into my kernel. It probably ought to fall back more gracefully.
pbxes.org give a valid DNS response for any A request under pbxes.org. Maybe _sip._sctp.pbxes.org being resolvable confuses sofia-sip into thinking that SCTP is usable, but I thought it only works for SRV records. I have filed a sofia-sip bug about this. Try to set the transport to TCP or UDP in the SIP account settings and see if it helps. Also try setting the outbound proxy to 'pbxes.org' explicitly.
Have they removed the sctp SRV record in pbxes.org? I'm just wondering what was their configuration that triggered the problem.
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