ESI Common Issues
Unable to forward calls on a registered SIP trunk
There is a known ESI/Clearfly limitation when forwarding calls with the original caller-ID on registered SIP trunks. There are a couple of workarounds:
- If preserving the caller-ID of the original caller is not necessary, you can disable ESI's Intelligent Call Forwarding functionality (programming function 166, field 10). This programming change will keep the ESI from forwarding the original caller-ID info on a trunk-to-trunk transfer.
- If preserving the caller-ID of the original caller is necessary, you can migrate to a static SIP trunk.
ESI is currently estimating that a fix should be available for this issue in Q2'13.
Post-dial Delay (PDD) when making outbound calls on a registered SIP trunk
There is a known signaling issue in which ESI phone systems re-use the branch parameter in their INVITE messages across different transactions. As a result, Clearfly's SBC will discard the non-spec INVITE messages and the call will not proceed until the T4 timer expires. From the end-user's perspective, this manifests as PDD. ESI is tracking this issue internally and it is expected to be resolved in Q1 2015.