[Serusers] Clearing fr_inv_timer_avp after failure route

[Evan Borgstrom]

Hey All,

	I have fr_inv_timer_avp pointing to an AVP named inv_timeout which 
users are allowed to set and everything is working fine except upon call 
forwarding from a failure route. Here's the situation...

- Call comes in for user at domain.com
- User at domain.com has inv_timeout set to 10s
- User at domain.com also has forward on unavailable to a PSTN number
- 10s of ringing to the user elapses
- The failure route kicks in and pushes the PSTN URI to a new branch
- avp_delete("inv_timeout"); is called
- avp_write("i:3600", "inv_timeout"); is called
- The PSTN number begins to ring
- 10s later SER sends a CANCEL to the PSTN gateway

	How do I properly clear the users preset inv_timeout and reset it to 1 
hour for the PSTN destination?

Thanks,
Evan