This is a new one. They dial in (from their Yealink t48G), hit 1 to hear the new message, then hit 8 to forward, then 1 to enter the extension number, and then it hangs up. I tried it from here with another t48G using the same template and firmware and it works fine. Both phones connect externally to the PBX from different locations.
Looking at the log I see a message about an incorrect format for one of the greetings but fixing that and trying several different extension numbers yields the same result. Not sure where to look. Below is the log.
[2020-03-13 12:04:32] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘vm-password.ulaw’ (language ‘en’)
[2020-03-13 12:04:35] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘vm-youhave.ulaw’ (language ‘en’)
[2020-03-13 12:04:36] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘digits/20.ulaw’ (language ‘en’)
[2020-03-13 12:04:36] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘vm-first.ulaw’ (language ‘en’)
[2020-03-13 12:04:37] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘vm-message.ulaw’ (language ‘en’)
[2020-03-13 12:04:38] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘/var/spool/asterisk/voicemail/default/282/INBOX/msg0000.slin’ (language ‘en’)
[2020-03-13 12:04:41] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘vm-forward.ulaw’ (language ‘en’)
[2020-03-13 12:04:42] VERBOSE[5564][C-000014c2] file.c: <SIP/282-00001677> Playing ‘vm-extension.ulaw’ (language ‘en’)
[2020-03-13 12:04:47] WARNING[5564][C-000014c2] format_wav.c: Not a supported wav file format (49). Only PCM encoded, 16 bit, mono, 8kHz/16kHz files are supported with a lowercase ‘.wav’ extension.
[2020-03-13 12:04:47] WARNING[5564][C-000014c2] file.c: Unable to open format wav
[2020-03-13 12:04:47] WARNING[5564][C-000014c2] file.c: Unable to open /var/spool/asterisk/voicemail/default/283/greet (format (ulaw)): No such file or directory
[2020-03-13 12:04:47] VERBOSE[5564][C-000014c2] pbx.c: Spawn extension (from-internal, *97, 118) exited non-zero on ‘SIP/282-00001677’
[2020-03-13 12:04:47] VERBOSE[5564][C-000014c2] pbx.c: Executing [h@from-internal:1] Macro(“SIP/282-00001677”, “hangupcall”) in new stack