[Users] show active calls

[Juha Heinanen]

JF writes:

 > You can have pre-paid SIP services without PSTN.

why?  i don't understand how anyone would subscribe to such a service.
how many email services you know that charge by the volume of email
messages sent?

 > Also, an IMS S-CSCF based on SER would require this in order to be
 > fully compliant to 3GPP standards, but probably this is of no
 > importance in the scope of this list.

3gpp uses "SIP" to implement a walled garden.  again, i have seen very
little interest for it in user community.  they simply use their nokia e
series phones as regular rfc3261 compliant phones, not 3gpp phones.

-- juha