IAX2 encryption do now work?

Hello! I have configured IAX2 trunk between two Asterisk servers using the following config:
iax.conf

[general]
autokill=yes
srvlookup=no
encryption=yes
forceencryption=yes

[serverB]
type=friend
context=iax2-trunks
delayreject=yes
host=192.168.1.38
auth=md5
username=serverA
secret=1to2
disallow=all
allow=alaw
trunk=yes
encryption=aes128

So i can call between servers, but as i can see, encryption does not work. At ;least I cant verify it. When I enable iax debug it send me this info:

[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: Tx-Frame Retry[000] – OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: Timestamp: 00016ms SCall: 17884 DCall: 00000 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: VERSION : 2
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLED NUMBER : 102
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CODEC_PREFS : (alaw)
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING NUMBER : 101
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING PRESNTN : 0
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING TYPEOFN : 0
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING TRANSIT : 0
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING NAME : 101
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: LANGUAGE : en
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: USERNAME : iax2-centos1
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: ENCRYPTION : 32769
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: FORMAT : 8
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: FORMAT2 : alaw
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CAPABILITY : 8
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CAPABILITY2 : alaw
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: ADSICPE : 2
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: DATE TIME : 2017-05-30 18:30:46
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c:
[May 30 18:30:46] VERBOSE[1975] chan_iax2.c: Rx-Frame Retry[ No] – OSeqno: 000 ISeqno: 001 Type: IAX Subclass: CTOKEN
[May 30 18:30:46] VERBOSE[1975] chan_iax2.c: Timestamp: 00016ms SCall: 00001 DCall: 17884 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1975] chan_iax2.c: CALLTOKEN : 51 bytes
[May 30 18:30:46] VERBOSE[1975] chan_iax2.c:
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: Tx-Frame Retry[000] – OSeqno: 000 ISeqno: 000 Type: IAX Subclass: NEW
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: Timestamp: 00017ms SCall: 17884 DCall: 00000 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: VERSION : 2
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLED NUMBER : 102
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CODEC_PREFS : (alaw)
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING NUMBER : 101
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING PRESNTN : 0
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING TYPEOFN : 0
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING TRANSIT : 0
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLING NAME : 101
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: LANGUAGE : en
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: USERNAME : iax2-centos1
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: ENCRYPTION : 32769
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: FORMAT : 8
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: FORMAT2 : alaw
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CAPABILITY : 8
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CAPABILITY2 : alaw
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: ADSICPE : 2
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: DATE TIME : 2017-05-30 18:30:46
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: CALLTOKEN : 51 bytes
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c:
[May 30 18:30:46] VERBOSE[1976] chan_iax2.c: Rx-Frame Retry[ No] – OSeqno: 000 ISeqno: 001 Type: IAX Subclass: AUTHREQ
[May 30 18:30:46] VERBOSE[1976] chan_iax2.c: Timestamp: 00013ms SCall: 02818 DCall: 17884 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1976] chan_iax2.c: AUTHMETHODS : 2
[May 30 18:30:46] VERBOSE[1976] chan_iax2.c: CHALLENGE : \x36\x34\x32\x34\x37\x32\x38\x32\x32
[May 30 18:30:46] VERBOSE[1976] chan_iax2.c: ENCRYPTION : 1
[May 30 18:30:46] VERBOSE[1976] chan_iax2.c: USERNAME : iax2-centos1
[May 30 18:30:46] VERBOSE[1976] chan_iax2.c:
[May 30 18:30:46] VERBOSE[1976][C-00000030] chan_iax2.c: TE-Frame Retry[000] – OSeqno: 001 ISeqno: 001 Type: IAX Subclass: AUTHREP
[May 30 18:30:46] VERBOSE[1976][C-00000030] chan_iax2.c: Timestamp: 00018ms SCall: 17884 DCall: 02818 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1976][C-00000030] chan_iax2.c: MD5 RESULT : 6415ec9f0a45450289e96271edb7b5f5
[May 30 18:30:46] VERBOSE[1976][C-00000030] chan_iax2.c:
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: Tx-Frame Retry[000] – OSeqno: 025 ISeqno: 038 Type: (95?) Subclass: 147
[May 30 18:30:46] VERBOSE[1969] chan_iax2.c: Timestamp: 1128729983ms SCall: 17884 DCall: 02818 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[3314][C-00000030] app_dial.c: – Called IAX2/iax2-centos2/102
[May 30 18:30:46] VERBOSE[1977] chan_iax2.c: Rx-Frame Retry[ No] – OSeqno: 225 ISeqno: 107 Type: CNG Subclass: 74
[May 30 18:30:46] VERBOSE[1977] chan_iax2.c: Timestamp: 2160165086ms SCall: 02818 DCall: 17884 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: RD-Frame Retry[ No] – OSeqno: 001 ISeqno: 002 Type: IAX Subclass: ACCEPT
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: Timestamp: 00014ms SCall: 02818 DCall: 17884 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: Unknown IE 000 : Present
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: Unknown IE 000 : Present
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c:
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: – Call accepted by 192.168.1.38 (format alaw)
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: – Format for call is (alaw)
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: TE-Frame Retry[-01] – OSeqno: 002 ISeqno: 002 Type: IAX Subclass: ACK
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: Timestamp: 00014ms SCall: 17884 DCall: 02818 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: Tx-Frame Retry[-01] – OSeqno: 096 ISeqno: 131 Type: (224?) Subclass: 228
[May 30 18:30:46] VERBOSE[1977][C-00000030] chan_iax2.c: Timestamp: 3446438069ms SCall: 17884 DCall: 02818 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1978] chan_iax2.c: Rx-Frame Retry[ No] – OSeqno: 219 ISeqno: 204 Type: (178?) Subclass: 18
[May 30 18:30:46] VERBOSE[1978] chan_iax2.c: Timestamp: 2783788592ms SCall: 02818 DCall: 17884 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1978][C-00000030] chan_iax2.c: RD-Frame Retry[ No] – OSeqno: 002 ISeqno: 002 Type: CONTROL Subclass: ANSWER
[May 30 18:30:46] VERBOSE[1978][C-00000030] chan_iax2.c: Timestamp: 00017ms SCall: 02818 DCall: 17884 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1978][C-00000030] chan_iax2.c: TE-Frame Retry[-01] – OSeqno: 002 ISeqno: 003 Type: IAX Subclass: ACK
[May 30 18:30:46] VERBOSE[1978][C-00000030] chan_iax2.c: Timestamp: 00017ms SCall: 17884 DCall: 02818 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[1978][C-00000030] chan_iax2.c: Tx-Frame Retry[-01] – OSeqno: 229 ISeqno: 102 Type: (91?) Subclass: 243
[May 30 18:30:46] VERBOSE[1978][C-00000030] chan_iax2.c: Timestamp: 1853412569ms SCall: 17884 DCall: 02818 [192.168.1.38:4569]
[May 30 18:30:46] VERBOSE[3314][C-00000030] app_dial.c: – IAX2/iax2-centos2-17884 answered SIP/101-00000008

Nothing about encrypting packets. What i’ve done wrong, or how can i verify that encryption works?
I use Asterisk v11