VoIP Security Checklist
for MSPs Heading Into Q4

As Q4 ramps up, MSPs are juggling end-of-year projects, client demands, and the inevitable uptick in cyberthreats. Hackers know the drill—holiday weekends, year-end deadlines, and short-staffed IT teams create perfect conditions for attacks.

VoIP systems are often the bullseye. Fraudsters love running up phone bills when no one’s watching, and they’re not shy about probing SIP ports during long weekends. The good news: with the right safeguards in place, you can keep your clients’ VoIP systems secure heading into the new year.

Here’s your 8-point Q4 VoIP security checklist—practical, MSP-friendly, and ready to use.

Turn on TLS for SIP signaling and SRTP for audio streams. Encryption keeps conversations private and prevents packet-sniffing attacks. Check On-Prem PBXs and endpoints, to make sure you’re enforcing modern ciphers (TLS 1.2+).

Treat VoIP like any other critical workload: behind firewalls and out of public view. Only allow traffic from trusted IP ranges, block unused ports, and keep phones off public IPs. Simple moves like denying public access to phone web GUIs via ports 80 and 443 can slam the door on opportunistic scans.

Firewall Rule Guide: https://voipdocs.io/en_US/faqs/ip-addresses-ports

SIP is the attacker’s playground. Shut down guest calls, block unused methods, and restrict SIP traffic to known carriers or subnets. (We handle these protections on our end, but for MSPs managing on-prem PBXs, this is a helpful step.)

Default logins? Gone. Weak passwords? Not on your watch. Every extension and device should use complex, unique credentials. In the OIT portal, you can enable MFA (multi-factor authentication) for user access and even use the Reset and Recycle a User feature to quickly secure accounts when employees leave.

How to Reset & Recycle a User: https://voipdocs.io/en_US/users/reset-and-recycle-a-user

Bonus: OIT auto-generates per-device SIP registration and provisioning passwords for every endpoint, adding another layer of protection by default

This primarily applies to on-prem PBXs, not OIT’s hosted service. If you’re running on-prem, keep PBX admin portals off the public internet. Require VPNs (or at least IP whitelisting) for remote phones and admins.

Attackers love long weekends. Behind the scenes, OIT continuously monitors and blocks malicious traffic before it ever reaches you. If you’re managing your own on-prem PBX, don’t just collect logs—use them. Set alerts for unusual spikes, late-night calls, or sudden international traffic.

Regularly check for device firmware updates and implement them after controlled testing. Make sure firewalls, routers, and computers with access to phone web GUIs are patched regularly. Keeping endpoints updated closes one of the biggest doors attackers love to exploit.

Stop using TFTP or open HTTP for device configs—it’s basically giving away SIP passwords in plain text. Use HTTPS with authentication or certificates when provisioning. (Good news: OIT manages secure provisioning on our side, but if you run standalone systems, it’s a must-have.)

Like this blog? Our monthly OIT Newsletter just dropped with even more insights, updates, and MSP-focused resources to help you crush Q4 and kick off 2026 strong. Don’t miss it!