We are using CUCM 10.5.2 and have SIP trunks. I have been fighting a problem where I have phones that are sending out a toll free number as their ani by putting the TFN in the "External Phone Number Mask" on the line page for the phones that need that listed as their call back. If I leave that field blank then the system sends their extension number. If I put a non TFN the call will go through no issues. I spoke with the SIP provider and they are telling me that because we are sending out a TFN and when calling a TFN from a TFN the SIP routers dont know how to handle it, or it will take it a minute or longer to connect or sometimes you get the operator intercept. The carrier also says this came about because of the FCC STIR/SHAKEN in an effort to eliminate some of the spam and robo calls. The carrier told me that I needed to add a p-change-header to the Inivte on on the call. I have no idea where to add or change this setting and if its a global change or individual change. Also, where do I make this change? Is there somewhere in the CUCM or is it on the SBC (cube) that this needs to be done or is it even possible.
thanks, Mark
