By default, the Telephony Session service rejects any incoming call containing an INVITE message with Nuance headers. (These contain “P-Nuance.”) Since Voice Platform uses these headers to convey information among its internal components, this precaution prevents a malicious party from performing unwanted actions on the Telephony Session service like placing outbound calls.

By setting a service property in the Management Station, you can specify a list of IP addresses from which the Telephony Session service can safely accept incoming calls containing these Nuance headers. The syntax is:

ts.TrustedSources = IP_Address1,IP_Address2,...IP_AddressN

If an incoming INVITE message contains Nuance headers, the Telephony Session service checks the originating IP address and rejects the call if that IP address is not in the TrustedSources list.

Set ts.TrustedSources to “all” (without quotes) to accept all incoming calls even if Nuance headers are in the INVITE message. Only do this if you’re on a secure network and you know for sure that no one from the outside can access the Telephony Session service directly.