MDR vs MSSP vs SOC-as-a-Service: Which Do You Need?

The difference between MDR and an MSSP comes down to action. Managed detection and response (MDR) is a service in which an external team investigates threats and responds to them, whereas a managed security service provider (MSSP) traditionally monitors and manages your security tools and passes alerts back to you. SOC-as-a-service is a way of buying the monitoring function itself, and what it includes depends entirely on the contract.

These terms are not standardised. Providers use them differently, and the same service can be labelled MDR by one vendor and SOC-as-a-service by another. This guide therefore compares them on the questions that decide outcomes: who watches, who responds, what they are permitted to do without phoning you, and what happens at 2am.

I am Caleb Adoh, Growth Marketing Manager at NetMonkeys, a Manchester-headquartered managed IT provider and Microsoft Solutions Partner. The guide is written for UK SMEs and mid-market organisations of roughly 20 to 250 staff, where the question is rarely whether to build a security operations centre and almost always which external model to trust.

MDR vs MSSP: what is the difference?

An MSSP is the older model. It typically runs or monitors firewalls, email security, log collection and similar tools, and raises tickets or alerts when something looks wrong. The investigation and the fix often land with your internal IT team or your IT provider. Some MSSPs have moved well beyond this, but alert-and-escalate remains the common baseline.

MDR is defined by the response step. Analysts triage and investigate detections, then act to contain the threat, or guide your team through doing so. Microsoft describes its own service in these terms: its analysts manage the incident queue around the clock, investigate on your behalf, and either take action or guide your team through the response (as at October 2026, per the Microsoft Learn documentation for Defender Experts MDR).

MSSP vs MSP

A managed service provider (MSP) runs your IT: helpdesk, devices, patching, Microsoft 365, backups. An MSSP specialises in security operations. Many organisations need both, and some providers offer both under one roof. The distinction that matters is staffing: a helpdesk technician fixing a laptop is not the same skill set as an analyst triaging a suspicious sign-in at 3am. If you already buy managed IT support, ask which security tasks sit inside it and which sit with a dedicated security team.

What is managed detection and response, and is MDR the same as EDR?

Managed detection and response combines technology (usually endpoint detection and response, plus other telemetry), human analysts who triage what the technology finds, and a defined response process. The human element is the point. Tools generate far more alerts than a small business can read.

MDR vs EDR

EDR is software. It records activity on devices, detects suspicious behaviour and gives responders the means to isolate a machine or stop a process. MDR is a service that uses EDR and, in most cases, other sources such as identity, email and cloud logs. Buying EDR gives you a smoke detector; buying MDR gives you someone to answer it.

Is MDR the same as managed EDR?

Not always. Managed EDR usually means a provider deploys and tunes the EDR platform and monitors endpoint alerts. MDR commonly extends the scope beyond endpoints and puts more weight on investigation and response. In practice the boundary blurs, so compare the written scope rather than the product name. Our page on managed EDR services sets out how we frame the endpoint layer.

Microsoft's service illustrates the split. For Microsoft Defender workloads its analysts take action or provide guided response; for supported third-party products they provide guidance only, and the customer remains responsible for items such as data connectors and data quality. Active-compromise incident response is a separate offering (as at October 2026, per the same Microsoft Learn page). Even at a large vendor, then, the contract defines what happens, not the acronym.

What is SOC-as-a-service, and what does it include that an MSSP doesn't?

A security operations centre (SOC) is the team, process and tooling that watches for attacks, investigates alerts and manages incidents. The NCSC describes a typical SOC as built around a SIEM that collects and correlates logs, with analysts, engineers and management around it, and notes that SIEM licensing can be costly. Building one in-house takes time and money; outsourcing avoids that, although external analysts may know your architecture less well and may respond more slowly than an internal team (see the NCSC blog post on whether you need a SOC, published July 2023).

SOC-as-a-service is that function delivered on subscription: shared analysts, shared tooling, your logs and alerts feeding in. It is a delivery model rather than a guarantee of response. Some SOC-as-a-service contracts include containment; many stop at triage and notification.

Where it differs from an MSSP

• Focus: SOC-as-a-service centres on detection, triage and investigation. An MSSP may also manage firewalls, patching of security tools and compliance reporting.
• Log and SIEM depth: SOC-as-a-service is often built on log correlation across many sources. MDR is often built on endpoint and identity telemetry.
• Response: neither label tells you. Check the contract.

For a managed SOC in the UK, also ask where analysts are based, where your data is stored and processed, and whether the SOC operates around the clock or only during office hours.

Comparison table: MDR, MSSP, SOC-as-a-service, managed EDR and MSP

The table shows typical positions. Individual providers vary, so treat it as a reading guide for proposals, not a statement about any one supplier.

The response-authority spectrum

• Alert only: the provider tells you. You decide and act.
• Guided response: the provider investigates and tells you exactly what to do. You carry it out.
• Active containment: the provider acts directly, for example isolating a device or disabling a compromised account, under pre-agreed rules.

Which model actually stops an attack?

No label stops an attack by itself. Prevention comes from configuration, patching, multi-factor authentication and user awareness. What the three models change is how long an intruder is active after prevention fails. The higher the authority and the faster the response, the less time to move through the network. That is why response authority outweighs the product label. Our cybersecurity best practices guide covers the preventive layer.

The contract, not the label, decides who acts first.

Who responds to a security alert at 2am? An illustrative timeline

This is an illustrative scenario, not a record of a real incident or a service-level commitment. It assumes a 120-person firm and a suspicious sign-in followed by unusual file activity.

The difference is not the speed of detection; it is the gap between knowing and acting. In the alert-only column the attacker has hours. In the guided column the gap depends on whether someone answers the phone. In the containment column the provider closes it, which is why the contract wording about who is allowed to act, and whether that includes disabling accounts, matters so much.

If you rely on a service desk for out-of-hours cover, check whether it includes security triage or only fault logging. Our 24/7 IT support helpdesk page explains the difference between round-the-clock IT support and round-the-clock security monitoring.

Which model suits a business of 20 to 250 staff?

Match the model to your in-house capability, not your headcount alone.

Do I need MDR, an MSSP or SOC-as-a-service for a 100-person business?

Worked example, with stated assumptions: a 100-person professional services firm, Microsoft 365, no dedicated security staff, an outsourced IT provider covering office hours. Nobody is on call at night, so an alert-only service would leave alerts waiting until morning. The sensible choice is MDR, or managed EDR with documented isolation rights, covering endpoints and Microsoft 365 identity. The provider acts out of hours; your IT provider handles recovery during the day. An MSSP or SOC-as-a-service becomes relevant if a client contract or regulator requires log retention and reporting.

Who actually contains a breach in an MDR contract?

Whoever the contract says. Under active containment it is the provider, within an agreed list of actions. Under guided response it is your team or IT provider, following the provider's instructions. Under alert only it is you. Also confirm who owns eradication and recovery, because most MDR contracts exclude full incident response, as Microsoft's own documentation does for active-compromise work.

Before choosing, a cyber security audit shows which controls and visibility you already have. Smaller organisations can start with our guidance on cybersecurity for small business.

How is each model priced, and which do cyber insurers prefer?

Pricing

Published prices vary widely and change often, so I will not quote figures. The common structures are:

• MDR and managed EDR: usually per user or per device, per month, with the endpoint licence either included or bought separately.
• SOC-as-a-service: often priced by log volume, number of sources or users, which can rise as you connect more systems.
• MSSP: usually a per-service or per-device fee for each managed tool, plus reporting.

Compare proposals on what is included: licences, onboarding, log storage, out-of-hours calls, containment actions and incident response hours. NetMonkeys quotes against your user, device and security needs, and you can request a scoped quotation.

Which security model do cyber insurers prefer?

I have not verified any insurer publishing a preference between MDR, MSSP and SOC-as-a-service, so I will not claim one. Insurers commonly ask about 24/7 monitoring and endpoint detection on proposal forms, and the wording differs between them. Read your own proposal form and ask your broker which answers it accepts. The NCSC cyber insurance guidance suggests asking what response services your insurer provides and whether Cyber Essentials or Cyber Essentials Plus can lower premiums. See our notes on cyber insurance and the Cyber Essentials certification service.

Questions to ask a provider: a buyer checklist

Use these in every tender, whichever label appears on the proposal.

Tooling ownership and exit deserve extra attention. Our guides on what to do when a provider withholds admin access and how to choose an IT support company cover the same principles for general IT. If you are weighing an internal hire against external cover, see outsourced IT support vs in-house IT.

Conclusion: choosing between MDR vs MSSP vs SOC-as-a-service

On MDR vs MSSP, the practical answer for most 20 to 250 person organisations is to buy response, not just visibility. MDR, or managed EDR with explicit containment rights, closes the gap between detection and action. An MSSP or SOC-as-a-service earns its place where logging, reporting or an existing security team drives the need. Whichever you choose, judge the contract by its response authority, its out-of-hours arrangements and who owns the tooling.

If you want a second opinion on a proposal, or help scoping cover alongside outsourced IT support, contact NetMonkeys and we will review it with you.

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