Depends on what hardware you run 5.0, for a IP400 you don't need a networking license and for a IP500 you do need a voice networking license.
IP Office can be set as a CO line on a ETSI PRI if Cisco cannot.
With IP400 I have done both and Qsig is best a it signals as internal calls, a ETSI PRI always signals as external calls.
You need to work with line shortcodes if using Qsig for incoming calls as Qsig calls don't route through the ICR tables.
Main reason for me was to use the IPO as a conference bridge.
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