[Freeswitch-users] FreeSWITCH offering SRTP on Re-INVITE

Andrew Cassidy andrew at cassidywebservices.co.uk
Thu May 17 20:48:08 UTC 2018

Good afternoon All,

I have experienced the following issue with Zoiper specifically (I have a
support ticket open with them currently) and was wondering if it's
something that could/should be fixed FreeSWITCH side.

If rtp_secure_media is set to optional, and SRTP is disabled on Zoiper,
when FreeSWITCH sends the Re-INVITE, it sends crypto lines. Zoiper then
replies with a 514 Unsupported Media Type and the timer refresh fails,
causing Zoiper to hang up the call.

My current feeling is that as Zoiper ignored the crypto on the initial
INVITE it should be them that then handles the Re-INVITE consistently by
also ignoring the crypto lines but I'm not familiar enough with the RFCs to
make a judgement.

The workaround is to either enable SRTP in Zoiper or don't set
rtp_secure_media to optional when Zoiper is in use.

Kind regards,

*Andrew Cassidy BSc (Hons) MBCS*
Managing Director

0330 44 55 960 <+443304455960> andrew at cassidyweb.co.uk www.cassidyweb.co.uk
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