Security options for Access environments

Hello,

Besdies TLS for securing communications in access environmets, what other options are there?

Is the SBC capable of encripting communitations using IPSEC in access deployments?, I understand peering is the most common form of implementation, but, have any of you guys tried/implemented in access?

What about VPN support?, Is this supported/recommended in the SBC for the same scenario?

I'm doing this query beause we've seen a number of events with the TCP queue in the SBC causing loss of sevice for the TLS endpoints (eventually the tls deployment was decreased since the outages were severe, so nowadays they are using udp or tcp for signalling). Some phones are VPN capable so I'd like to explore the possibility of deploying this feature towards the SBC, maybe anyone of you guys have tried it or can provide another options for securing the communications.