An internet telephony call analyzer receives call information from endpoint and intermediate network devices, corrects timestamp errors in the records, stores the records, and identifies records associated with a single call session between two endpoint devices in the network. The timestamp errors may be corrected by applying a time differential correction to a call start timestamp and call stop timestamp of the record if the timestamp in the record differs from a system timestamp when the record was received by the call analyzer. Call information records associated with the same call session may be matched by identifying records with the same SIP call ID, the same SSRC ID and call start timestamps within a predetermined time interval of each other.