Source record · tier 1 standards and regulators
RFC 3398: Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping
- Publisher
- IETF / RFC Editor
- URL
- https://www.rfc-editor.org/rfc/rfc3398.html
- Published
- 2002-12-01
- Updated
- unknown
- Accessed
- 2026-09-24
- HTTP status
- 200
- License
- IETF Trust Legal Provisions; short excerpts and locators only
Source notes citing this source
- Because several distinct ISUP causes collapse to SIP 503 under RFC 3398, an escalation that reports only the SIP status code loses the PSTN-side reason; including any Q.850 cause from a Reason header preserves it. inferred in context
- RFC 3398 maps ISUP cause 1 (unallocated number) and cause 3 (no route to destination) to SIP 404 Not Found. in context
- RFC 3398 maps ISUP cause 127 (interworking unspecified) to SIP 500 Server Internal Error. in context
- RFC 3398 maps ISUP cause 17 (user busy) to SIP 486 Busy Here. in context
- RFC 3398 maps ISUP cause 18 (no user responding) to SIP 408 Request Timeout and cause 19 (no answer from user) to SIP 480 Temporarily Unavailable. in context
- RFC 3398 maps ISUP causes 34, 38, 41, 42 and 47 (no circuit, network out of order, temporary failure, switching equipment congestion, resource unavailable) to SIP 503 Service Unavailable. in context
- RFC 3398 maps ISUP ANM or CON (answer) to SIP 200 OK. in context
- A release cause that crosses two RFC 3398 gateways is not guaranteed to survive intact; for example cause 34 becomes SIP 503 on the first gateway and SIP 503 becomes cause 41 on the second. inferred in context
- RFC 3398 maps ISUP release cause 1 (unallocated number) to SIP 404 Not Found. in context
- RFC 3398 maps ISUP release cause 17 (user busy) to SIP 486 Busy Here. in context
- RFC 3398 maps ISUP release cause 18 (no user responding) to SIP 408 Request Timeout. in context
- RFC 3398 maps ISUP release cause 19 (no answer from user) to SIP 480 Temporarily Unavailable. in context
- RFC 3398 maps ISUP release cause 27 (destination out of order) to SIP 502 Bad Gateway. in context
- RFC 3398 maps ISUP release cause 28 (address incomplete) to SIP 484 Address Incomplete. in context
- RFC 3398 maps the resource-unavailable ISUP causes 34, 38, 41, 42 and 47 to SIP 503 Service Unavailable. in context
- For SIP-bridging (PSTN to SIP to PSTN transit), RFC 3398 requires the SIP messages to carry the ISUP message as a MIME body so it can be reproduced at the far gateway. in context
- In the SIP-to-ISUP direction RFC 3398 maps SIP 486 Busy Here to ISUP cause 17 (user busy). in context
- In the SIP-to-ISUP direction RFC 3398 maps SIP 503 Service Unavailable to ISUP cause 41 (temporary failure). in context
- Under RFC 3398, an ISUP cause value not listed in the mapping table SHOULD be answered with SIP 500 Server Internal Error. in context
- Under RFC 3398, a SIP status code not listed in the mapping table SHOULD result in an ISUP REL with cause 127 (interworking unspecified). in context
- Because standards and gateway defaults collapse several distinct PSTN causes into 404, the SIP code alone cannot tell an unassigned number from a routing failure; the Q.850 cause in a Reason header, where present, is the better discriminator. inferred in context
- RFC 3398 maps ISUP cause 1 (unallocated number) received from the PSTN to SIP 404 Not Found. in context
- RFC 3398 maps ISUP cause 22 (number changed) to 410 Gone, or to 301 Moved Permanently when a diagnostic carrying the new number is present. in context
- RFC 3398 maps ISUP cause 28 (address incomplete / invalid number format) to SIP 484 Address Incomplete. in context
- RFC 3398 advises gateways facing overlap dialling to implement timers so that all digits have been collected before an INVITE is transmitted. in context
- RFC 3398 maps ISUP causes 2 (no route to network), 3 (no route to destination) and 26 (non-selected user clearing) to SIP 404 Not Found. in context
- RFC 3398 places overlap dialling mechanisms (use of the ISUP Subsequent Address Message) outside its scope. in context
- RFC 3398 maps ISUP cause 18 (no user responding) received from the PSTN to SIP 408 Request Timeout. in context
- RFC 3398 says that when ISUP timer T7 expires before an ACM or CON is received, the gateway should send 504 Server Timeout to the SIP side, not 408. in context
- Under RFC 3398, when an ISUP ACM carries a Backward Call Indicators value of subscriber free, the gateway SHOULD send 180 Ringing toward SIP. in context
- Under RFC 3398, on receipt of an ISUP ANM or CON the gateway SHOULD send 200 OK toward SIP, which marks answer. in context
- RFC 3398 maps ISUP cause value 1 (unallocated number) received from the PSTN to the SIP response 404 Not Found. in context
- RFC 3398 maps ISUP cause value 102 (recovery on timer expiry) to the SIP response 504 Gateway Timeout. in context
- RFC 3398 maps ISUP cause value 17 (user busy) to the SIP response 486 Busy Here. in context
- RFC 3398 maps ISUP cause value 18 (no user responding) to the SIP response 408 Request Timeout. in context
- RFC 3398 maps ISUP cause value 19 (no answer from user) to the SIP response 480 Temporarily Unavailable. in context
- RFC 3398 maps ISUP cause value 21 (call rejected) to the SIP response 403 Forbidden. in context
- RFC 3398 maps ISUP cause value 28 (address incomplete) to the SIP response 484 Address Incomplete. in context
- RFC 3398 maps ISUP cause values 34 (no circuit available), 38 (network out of order) and 41 (temporary failure) to the SIP response 503 Service Unavailable. in context
- Under RFC 3398, when an early ACM (called party status no indication) is received, the gateway SHOULD send 183 Session Progress toward SIP. in context
- Under RFC 3398, an ISUP cause value not listed in the mapping table SHOULD produce the default SIP response 500 Server Internal Error. in context
- RFC 3398 notes that ISUP has a presentation-restriction concept for the calling number and says gateways MAY support more sophisticated SIP privacy systems, without specifying a detailed mapping. in context
- RFC 3398 (December 2002) is a Standards Track IETF document describing how a gateway maps ISUP signalling to SIP and SIP to ISUP. in context
- RFC 3398 places overlap dialling (ISUP Subsequent Address Messages) outside its scope and assumes gateways collect all digits with timers before sending an INVITE. in context
- Under RFC 3398, a SIP status code not listed in the SIP-to-ISUP table SHOULD be mapped to the default ISUP cause 16 (normal clearing). in context
- RFC 3398 maps a SIP 404 Not Found final response to ISUP cause value 1 (unallocated number) toward the PSTN. in context
- RFC 3398 maps SIP 480 Temporarily Unavailable to ISUP cause value 19 (no answer from user). in context
- RFC 3398 maps SIP 484 Address Incomplete to ISUP cause value 28 (address incomplete). in context
- RFC 3398 maps both SIP 486 Busy Here and SIP 600 Busy Everywhere to ISUP cause value 17 (user busy). in context
- RFC 3398 maps SIP 503 Service Unavailable to ISUP cause value 38 (network out of order). in context
- RFC 3398 maps SIP 603 Decline to ISUP cause value 21 (call rejected). in context
Cite this source record
APA
WarmTransfer. (2002, December 1). RFC 3398: Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping. WarmTransfer. https://warmtransfer.net/knowledge/sources/rfc-3398-isup-sip-mapping
BibTeX
@misc{warmtransfer-rfc-3398-isup-sip-mapping,
title = {RFC 3398: Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping},
author = {{WarmTransfer}},
year = {2002},
url = {https://warmtransfer.net/knowledge/sources/rfc-3398-isup-sip-mapping},
note = {IETF / RFC Editor, accessed 2026-09-24}
}