VoIP Billing on a Softswitch: Prepaid, Postpaid & Real-Time CDR

Accurate VoIP billing turns routed minutes into revenue. On a softswitch, every CDR (Call Detail Record) feeds rating, balances, and finance exports.

How billing works

When a call ends, the switch records CLI/CLD, duration, disconnect cause, customer and vendor, and applied rates. The billing engine rates the CDR and updates prepaid or postpaid balances.

Prepaid vs postpaid

Prepaid — balance must cover the call before or as it completes; common for wholesalers, calling cards, and high-risk accounts.

Postpaid — invoicing on a cycle from aggregated CDRs; common for contracted carriers with credit limits.

Many platforms support both with shared routing and reporting.

Rating essentials

• Rate decks per prefix with effective dates and billing increments (6+6, 1+1)
• Tariff plans per customer or product line
• Rounding rules matching commercial terms
• Automated vendor rate import to avoid manual lag

Operational visibility

Finance needs accurate CDRs; operations needs them sooner:

• Live balances and credit warnings
• Margin by destination, vendor, and customer
• CDR search for disputes
• Alerts when balances cross thresholds

Quality monitoring ties ASR drops to revenue risk on the same data.

Common failures

• Delayed CDRs that drive invoice disputes
• Wrong prefix lengths causing systematic under-billing
• Poor disconnect-code mapping for failed calls
• Separate billing systems that drift from routing

Summary

Billing on a softswitch should be real-time, prefix-accurate, and visible to both finance and NOC — especially when prepaid exposure is high.