First Start
At the First you must configure the phone settings.
Configure the Phone
1) Go to the Settings > Phone
Fill all the login informations for the Phone. Click the Apply Button to apply the change

Configure the phone Options
2) Go to the Settings > Phone Option
Fill all the login informations for the the voicemail . Click the Apply Button to apply the change

Note:
- You must create an IAX account for the Voix phone or the phone won’t work.
- If you use Voice Mail a VM context must exist, In the IAX and SIP conf the user that use voicemail must have the definition parameter "mailbox" for example 'mailbox=123@yourVMcontext.
There are just few conventions to use with Voix Phone:
1) the extension must be numeric es. [123]
2) the callerid must be in the format "name <extension>"
example of Extension in you SIP or IAX.conf:
[123]
host=dynamic
username=123
qualify=no
notransfer=no
secret=xxxxxxxxxx
type=friend
auth=md5
context=your extensions context
dtmfmode=rfc2833
callerid=pippo <123> ;<< The cli must be in this format
mailbox=123@your voicemail context
requirecalltoken=no ;<< Disable call token for iax extension
disallow=all
allow=gsm
deny=0.0.0.0/0.0.0.0
permit=192.168.1.0/255.255.255.0
Voix Phone use The MD5 encryption.