Session timer - call rejected with 420 Bad extension

Hi,

we are running on Acme Packet OS VM SCZ8.3.0 MR-1 Patch 7 (Build 292).

we have an issue related to sesion timer required. the call is dropped after 15 min (1800 sec). I know that we need to allow Timer header via sip feature. so we have created it:

sip-feature

    name                  timer

    realm                  Realm-xxxx

    support-mode-inbound          Pass

    require-mode-inbound          Pass

    proxy-require-mode-inbound       Pass

    support-mode-outbound          Pass

    require-mode-outbound          Pass

    proxy-require-mode-outbound       Pass

sip-interface

    realm-id                Realm-xxxx

    sip-port

        address                 1.3.5.8

        transport-protocol           TCP

        allow-anonymous             registered

    sip-port

        address                 1.3.5.8

        allow-anonymous             registered

    nat-traversal              always

    registration-caching          enabled

    options                 reg-via-key

    out-manipulationid           ACME_NAT_TO_FROM_IP

    implicit-service-route         enabled

    enforcement-profile           BLOCK-REFER

Here is the sip trace: 1.3.58 is sbc sip-interface & 1.0.0.21 is the Customer PBX