Go to: PBX > PBX Settings > Trunks. Then click “Add SIP Trunk”.
PLEASE NOTE: All incoming settings are blank!
-- General Settings -- Outbound Caller ID: 99051000xxxxxx – Skype Connect registration ID Maximum Channels: 1 – The number of channels you purchased from Skype. -- Outgoing Settings -- Trunk Name: SkypeConnect – This can be whatever you want PEER Details: username=99051000xxxxxx ; This is your Skype Connect registration ID secret=xxxxxxxx ; This is your Skype Connect registration password type=peer qualify=yes insecure=invite host=sip.skype.com fromdomain=sip.skype.com disallow=all allow=ulaw&gsm&alaw context=from-trunk fromuser=99051000xxxxxx ; This is your Skype Connect registration ID -- Registration -- Registration String: 99051000xxxxxx:**firstname.lastname@example.org/99051000xxxxxx **password** is your Skype Connect registration password.
Click “Submit Changes”… Apply Changes.
This is all you need for setting up the registration to Skype Connect; you should now be able to log into Skype control panel and see “SIP user successfully registered at sip.skype.com”. Make sure you have enough credit allocated to the SIP trunk in the Skype Manager Control Panel.
Outbound Calling – Go to: PBX > PBX Settings > Outbound Routes.
From here you want to map your outbound calls to go across your Skype Connect trunk that we setup earlier. Either create a new route or edit the default one… Under “Dial Patterns” (we’ll use dial 9 for an outside line/use this trunk) add “9|.” minus the quotes. Set the “Trunk Sequence” to “SIP/SkypeConnect”. Click “Submit Changes”… Apply Changes.
Source: Configure Skype for SIP