+1 vote

zoiper when using srtp sends the below crypto in SDP

a=crypto:5 AES_256_CM_HMAC_SHA1_80
a=crypto:6 AES_256_CM_HMAC_SHA1_32
a=crypto:3 AES_192_CM_HMAC_SHA1_80
a=crypto:4 AES_192_CM_HMAC_SHA1_32
a=crypto:1 AES_CM_128_HMAC_SHA1_80
a=crypto:2 AES_CM_128_HMAC_SHA1_32

whereas freeswitch prefers


so in this case only the below 2 match and the rest freeswitch says unsupported


the rest dont match because the placement of AES_CM_192 in FS and AES_192_CM in zoiper

may i ask why is this the case that zoiper is sending same crypto name with the text all misplaced making it impossible for FS to match and use?

in Android by (130 points)

1 Answer

0 votes


We spoke to the FS team and found to be using diffent naming conventions for the negotiations. The 2 RFC´s use different names. Both Zoiper and FS will add a workaround to support both in future versions.

by (34.3k points)
edited by

im on the latest master of FS so still not seeing the patch for this, i see the bug request FS-11052 created for FS but the pull request isnt public so cant manually patch FS to test it coz its not visible

I too am seeing this issue on Zoiper 5.2.19 and Freeswitch 1.6.20. Older Zoiper clients work with this version of Freeswitch, but apparently in Zoiper 5 and FS 1.6 both sides are incomatible with each other.

It doesn't look like Freeswitch will be compatible with Zoiper for a while as they've closed the code based for 2 years.

How do we get the older version of zoiper in the app stores ? We need srtp working...

This is the version that runs 256


Other sip clients work with FS / fusion on 128.

An older phone just downloaded the older version on the Google play store. How do we tell Google we are an older phone ?

This is the link that does work. Samsung s7


You can also configure Freeswitch 1.6 to work with Zoiper 5 and latest Android versions, see my blog for more info:


But basically you set the

rtp_secure_media variable to AES_CM_128_HMAC_SHA1_80

I am facing the same issue. After upgrading to Zoiper 5, it has stopped working with my FreeSWITCH Version 1.6.19.

Outgoing calls give an error message "Required Crypto missing in SDP".

I believe the guide from "tomp", above, will be very useful. :-) 

Thanks! According to Mike Jerris over at the Freeswitch team, the fix for this is now in the master branch of Freeswitch, although it hasn't made it into the 1.8.1 release. It should be in the next one, but I'm not sure when that will be.

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