An online charging system (OCS) authorizes and rates usage in real time: data sessions, voice calls, SMS and events. It keeps customer balances, applies allowances and bundles, and tells the network when to stop a session. For prepaid, IoT and most modern MVNO offers, it sits at the heart of the business.
Because it is so central, replacing an OCS is expensive and risky. That makes the first choice important. These are the questions I work through with MVNOs and MVNEs before shortlisting vendors.
1. Can it charge on your host network, today and on 5G?
Your OCS must speak the charging interfaces your host operator exposes. In 4G that usually means Diameter Gy (data) and Ro (voice and messaging). For 5G standalone, charging moves to the Converged Charging System and the Charging Function (CHF) over the Nchf service-based interface. Ask vendors to show live references on both, not just a roadmap slide.
- Which host operators and network vendors has the OCS been integrated with?
- Does it support 5G converged charging (CHF) in production?
- How does it handle session failover and quota management when the network or OCS is under load?
2. How flexible is rating and product configuration?
MVNOs compete on offers. Your marketing team should be able to launch a new bundle, add-on or promotion without a vendor change request. Check how products are configured, how long a typical new tariff takes and whether business users can do it safely with testing and approval.
- Shared and family balances, rollover, throttling after allowance, time-of-day and zone pricing.
- Recurring charges and one-time fees, not just usage.
- A product catalog that is shared with CRM and billing, so offers are defined once.
3. Does it fit IoT and multi-operator scenarios?
IoT changes the economics: many connections, small amounts of data and low revenue per SIM. The OCS must scale to millions of subscriptions at a low cost per connection. If you use several host operators or Multi-IMSI SIMs, it must rate usage per sponsor network and keep one view of the customer. See Multi-IMSI explained for what that involves.
4. How well does it integrate with the rest of your BSS?
An OCS never works alone. It needs CRM, provisioning, billing, payments, notifications and policy control (PCRF or PCF). Ask for open, documented APIs, event streams for balance and usage changes, and proven integrations with the systems you already have or plan to buy.
5. Is it built for how you want to operate?
- Deployment: SaaS, your own cloud or on premises. Cloud-native, container-based platforms scale more easily.
- Multi-tenancy: essential if you are an MVNE serving several brands.
- Operations: monitoring, alarms, audit logs and how upgrades are done without downtime.
- Security: access control, encryption and segregation of duties for rating and balance changes.
6. What will it really cost over five years?
License models vary: per subscriber, per transaction, per active subscriber or fixed capacity. Model your growth for five years, including IoT connections that generate little revenue. Add implementation, integration, hosting, support and the internal team you need. The cheapest offer on day one is often not the cheapest over the life of the platform.
7. How will you migrate?
If you are replacing an existing OCS, plan the migration early: balances, bundles, history and in-flight sessions. A phased migration by customer group, with reconciliation between old and new systems, reduces risk.
A simple way to decide
Score each vendor on these areas, weight them by what matters most to your business, and insist on a proof of concept against your real use cases. Talk to reference customers who look like you in size and business model.
If you are planning an OCS selection or replacement, I am happy to help with requirements, the RFP, vendor evaluation and the proof of concept.
