VOIP Phones re-registering after v6.3 to 7.x upgrade

[bhinshaw21]

Running CallManager 3.3 at HQ facility with 3 remote sites that register phones via IPSEC tunnels to HQ. Recently tried upgrading my HQ Pix 515 from 6.3(3) to 7.0(1) and it caused the phones to start reregistering sporadically at only the remote sites. HQ phones were ok. Any ideas?

[a-vazquez]

Probably,reason for the phones at remote sites reregister might be upgradation of PIX at HQ leads to resetting of ipsec tunnel.