In PJSIP 2.12.1, PJSIP_UDP_SIZE_THRESHOLD defaults to 1300 bytes, and requests larger than it are sent over TCP when TCP switching is enabled.
Checked 2026-10-02
- Vendor
- Teluu
- Product
- PJSIP
- Subsystem
- SIP transport
- Deployment
- on-premises
- Region
- not restricted
- Release range
- 2.12.1
- Checked
- 2026-10-02
Sources
- Group PJSIP_CONFIG - PJSIP Project 2.12.1 documentation — PJSIP project (Teluu) · tier 2 current vendor documentation · PJSIP_UDP_SIZE_THRESHOLD
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting failed calls caused by large SIP messages over UDP: source note sip-fragmentation-troubleshooting-pjsip-udp-threshold-1300. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-fragmentation-troubleshooting-pjsip-udp-threshold-1300
BibTeX
@misc{warmtransfer-claim-sip-fragmentation-troubleshooting-pjsip-udp-threshold-1300,
title = {Troubleshooting failed calls caused by large SIP messages over UDP: source note sip-fragmentation-troubleshooting-pjsip-udp-threshold-1300},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-fragmentation-troubleshooting-pjsip-udp-threshold-1300},
note = {Source note sip-fragmentation-troubleshooting-pjsip-udp-threshold-1300, checked 2026-10-02}
}