There’s a cool feature in PFCP that allows you to redirect traffic, which I’ve written about before.

But there’s a funky thing that’s left me scratching my head, in the Redirect information IE, you can set a SIP URI.

That’d be great and all, but PFCP is all about packets not about calls.

So what’s the deal?

Had I uncovered some Machiavellian plot to move channel-associated-signaling onto PFCP instead of TDM links as God intended?

Well, no…

The Redirect Information in PFCP comes from the Redirect Information in Diameter, that’s how your OCS can tell your SMF or your PGW-C (or your TAS) – hey this session is all out of usage, and should be redirected.

Of course, PFCP is just all about packets, but Diameter has a foot in both camps, Gy and Ro are both on Diameter.

So when the 3GPP specced this IE, they just copied the encoding from the Redirect Address Type AVP in Diameter charging base, which has support for calls.

I can put down my pitchfork and go and hug my E1 links knowing they’re safe.