You're trying to establish an IPSec session but for some reason it looks like the phone or the ASA (likely the phone) is also trying to establish an L2TP connection once the tunnel is up. The IPsec session doesn't understand L2TP so it terminates the connection.
it may be normal for the phone - but the ASA will not accept an L2TP connection without a valid profile. Since you phone is trying an IPSEC session - and this type of profile is configured, you will only get so far.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...