REST phone app voicemail not working

I have Mitel 6867i phones. The voicemail app is not working. When going into settings, trying to record name and messages. You are prompted with the beep, record and save, but the recording is empty.

I just tried this and I was able to record my name and greetings. What do you asterisk logs show when trying this?

Where is the log you are talking about?

That Asterisk logs in /var/log/asterisk

== Using SIP RTP TOS bits 184
== Using SIP RTP CoS mark 5
[2015-11-06 10:53:52] ERROR[4471][C-000001ce]: pbx.c:4442 ast_func_write: Function PJSIP_HEADER not registered
== Extension Changed 2710[ext-local] new state Ringing for Notify User 2734
== Extension Changed 2710[ext-local] new state Ringing for Notify User 2000
== Extension Changed 2710[ext-local] new state Ringing for Notify User 2001
== Extension Changed 2710[ext-local] new state Ringing for Notify User 2715
> 0x3c074c0 – Probation passed - setting RTP source address to 192.168.1.18:3000
> 0x3c074c0 – Probation passed - setting RTP source address to 192.168.1.18:3000
== Extension Changed 2710[ext-local] new state InUse for Notify User 2734
== Extension Changed 2710[ext-local] new state InUse for Notify User 2000
== Extension Changed 2710[ext-local] new state InUse for Notify User 2001
== Extension Changed 2710[ext-local] new state InUse for Notify User 2715
[2015-11-06 10:53:52] ERROR[4471][C-000001ce]: pbx.c:4442 ast_func_write: Function PJSIP_HEADER not registered
> Channel SIP/2710-000001ff was answered.
> Launching AGI(vm-greeting-record.php,/var/spool/asterisk/voicemail/default/2710/,greet) on SIP/2710-000001ff
– Launched AGI Script /var/lib/asterisk/agi-bin/vm-greeting-record.php
> 0x3c074c0 – Probation passed - setting RTP source address to 192.168.1.18:3000
– <SIP/2710-000001ff> Playing ‘beep.ulaw’ (language ‘en’)
– AGI Script Executing Application: (Playback) Options: (vm-msgsaved)
– <SIP/2710-000001ff> Playing ‘vm-msgsaved.ulaw’ (language ‘en’)
– <SIP/2710-000001ff>AGI Script vm-greeting-record.php completed, returning 0