Source note · SIP ALG problems on firewalls and routers
If a SIP device sends SDP whose o= (owner/creator) IP differs from the c= (connection) IP, the ASA with PAT may not translate the o= address properly because the o= field has no port.
Checked 2026-09-25
- Vendor
- Cisco
- Product
- Cisco Secure Firewall ASA
- Subsystem
- application inspection
- Deployment
- on-premises
- Region
- not restricted
- Release range
- ASA 9.23
- Checked
- 2026-09-25
Sources
- CLI Book 2: Cisco Secure Firewall ASA Firewall CLI Configuration Guide 9.23 - Inspection for Voice and Video Protocols — Cisco Systems · tier 2 current vendor documentation · SIP Inspection > PAT Limitations for SIP Inspection
Cite this note
APA
WarmTransfer. (2026, September 25). SIP ALG problems on firewalls and routers: source note sip-alg-problems-asa-sdp-o-line. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-alg-problems-asa-sdp-o-line
BibTeX
@misc{warmtransfer-claim-sip-alg-problems-asa-sdp-o-line,
title = {SIP ALG problems on firewalls and routers: source note sip-alg-problems-asa-sdp-o-line},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-alg-problems-asa-sdp-o-line},
note = {Source note sip-alg-problems-asa-sdp-o-line, checked 2026-09-25}
}