(I am actually using Sipnet and Zadarma on my FreeSWITCH server)
Sipnet.ru allows you to forward all incoming calls to a SIP URI. Also it allows creating sub-accounts. So, you create as many sub-accounts as you need, and set the forwarding of all calls to some unique URI, like vasya-pupkin@yourdomain.com
Then in your FreeSWITCH configuration, you create a new public extension:
File: conf/dialplan/public/50_users.xml
<include>
<extension name="pub_vasya-pupkin">
<condition field="destination_number" expression="^vasya-pupkin$">
<action application="transfer" data="1007 XML default"/>
</condition>
</extension>
so all calls to vasya-pupkin@yourdomain.com will be transferred to 1007 internal extension.
Fother SIP provider which don;t support forwarding (zadarma.com, for example), you create a SIP profile and use "extension" parameter to specify which extension in your public profile should be used:
File: conf/sip_profiles/external/zadarma.xml
<gateway name="zadarma_59555">
<param name="username" value="59555"/>
<param name="password" value="*******"/>
<param name="extension" value="vasya-pupkin"/>
<param name="expire-seconds" value="125"/>
<param name="register" value="true"/>
<param name="register-transport" value="udp"/>
<param name="proxy" value="sip.zadarma.com"/>
<param name="retry-seconds" value="30"/>
<param name="caller-id-in-from" value="false"/>
<param name="ping" value="27"/>
</gateway>
I've got some more practical examples in my blog, just in case.
Best Answer
I stumbled upon this question when I where looking for some answers of my own, and decided to answer your question.
In Bluebox you need to creative a number and then link it to your voicemail box. You start by adding a new feature code in "Applications" -> "Feature Codes" and click on "Add Feature Code". Then you choose "Check Voicemail" in Feature. Then under "Number assignment" you click on "Add Assignment" and then on "Add Number". In the pop-up box you fill in the number you want to link to Voicemail. For security you can choose to make the voicemail only accessed internally. After you have saved your new number you can save your newly created feature code and your access to the voicemail system.
I hope this helps..
Best Regards