I am using FreeSWITCH demo configuration to test SRTP calls. I am placing a call between endpoint 1000 and 1001. The call works fine when SRTP is disabled on the softphones. The problem starts when I enable SRTP on the softphones. I also enabled SRTP on FreeSWITCH server, by including the following command in vars.xml:

<X-PRE-PROCESS cmd="set" data="sip_secure_media=true"/>

When I try to place a call between the two endpoints now, I end up with one side immediately hanging up.

Specifically, the error seems to be:
[WARNING] switch_core_media.c:4035 Declining invite with only SAVP because secure media is administratively disabled

Followed by:
[NOTICE] sofia.c:7742 Hangup sofia/internal/1001@10.10.10.112:5060 [CS_CONSUME_MEDIA] [INCOMPATIBLE_DESTINATION]

Couldn't find any info on how to resolve this issue online.

Here's the relevant log:
2016-03-18 09:45:21.664536

[INFO] switch_rtp.c:3605 Activating Audio Secure RTP SEND
[DEBUG] switch_core_sqldb.c:2607 Secure Type: srtp:sdes:AES_CM_128_HMAC_SHA1_80
[INFO] switch_rtp.c:3583 Activating Audio Secure RTP RECV
[DEBUG] switch_core_sqldb.c:2607 Secure Type: srtp:sdes:AES_CM_128_HMAC_SHA1_80
[NOTICE] sofia_media.c:92 Pre-Answer sofia/internal/1000@10.10.10.77!
[DEBUG] switch_channel.c:3461 (sofia/internal/1000@10.10.10.77) Callstate Change RINGING -> EARLY
[DEBUG] mod_sofia.c:2330 Ring SDP:
v=0
o=FreeSWITCH 1458288533 1458288534 IN IP4 10.10.10.77
s=FreeSWITCH
c=IN IP4 10.10.10.77
t=0 0
m=audio 20188 RTP/SAVP 0 101
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv
a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:uhco9Z9FgciE1vh5LQqGyNXxts0etxavW51gJKVP

[DEBUG] switch_ivr_originate.c:1274 Raw Codec Activation Success L16@8000hz 1 channel 20ms
[DEBUG] switch_core_codec.c:221 sofia/internal/1000@10.10.10.77 Push codec L16:100
[DEBUG] switch_ivr_originate.c:1343 Play Ringback Tone [%(2000,4000,440,480)]
[DEBUG] sofia.c:6756 Channel sofia/internal/1000@10.10.10.77 entering state [early][183]
[DEBUG] switch_rtp.c:6645 Correct audio ip/port confirmed.
[DEBUG] sofia.c:6756 Channel sofia/internal/1001@10.10.10.112:5060 entering state [completing][200]
[DEBUG] sofia.c:6766 Remote SDP:
v=0
o=VOCAL 61793 12653 IN IP4 10.10.10.112
s=-
c=IN IP4 10.10.10.112
t=0 0
m=audio 1442 RTP/SAVP 0
a=rtpmap:0 PCMU/8000
a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:i7qQOAKGWeBs/QtXQcYRD3g7u2pGv/BDqrvKE6Av
a=ptime:20

[DEBUG] sofia.c:6756 Channel sofia/internal/1001@10.10.10.112:5060 entering state [ready][200]
[WARNING] switch_core_media.c:4035 Declining invite with only SAVP because secure media is administratively disabled
[NOTICE] sofia.c:7742 Hangup sofia/internal/1001@10.10.10.112:5060 [CS_CONSUME_MEDIA] [INCOMPATIBLE_DESTINATION]
[DEBUG] sofia.c:1355 Channel is already hungup.

2016-03-18 09:45:26.303802