Calls fail to merge correctly when the B-leg 100 Trying (which lacks the callidmerge_header) arrives at the receiver before the INVITE.

[aqsyonis]

We are using a sender/receiver setup in VoIPmonitor, where the callidmerge_header is used to link the A-leg with the B-leg.

In certain scenarios, the receiver VoIPmonitor instance receives the 100 Trying response for the B-leg just a few milliseconds before the corresponding INVITE:

INVITE
Arrival Time: Apr 18, 2025 18:04:47.026086 UTC
100 Trying
Arrival Time: Apr 18, 2025 18:04:47.025242 UTC

Since the 100 Trying does not carry the callidmerge_header, VoIPmonitor treats it as a separate call and creates a new call file, causing the following packets to be stored incorrectly.

However, when the B-leg INVITE containing the callidmerge_header arrives first, VoIPmonitor successfully links the A-leg and B-leg, processing the call as expected.

Expected Behavior:
VoIPmonitor should use the INVITE as the reference point for selecting the pcap file, rather than the first packet received.

[voipmonitor]

Hello,

please attach sample pcap file

[aqsyonis]

Hi,

I’ve sent both PCAP files (A leg and B leg) to you via private email. Thanks.