CUBE Third-Party Interoperability Fax Guidelines

Publisher

Cisco

URL

https://www.cisco.com/c/en/us/support/docs/voice/t38/116280-configure-cube-00.html

Published

2013-08-14

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

Cisco website terms of use; all rights reserved; no-redistribution; short excerpts and locators only

Source notes citing this source

• For a T.38 re-INVITE rejected with SIP 488 on CUBE, Cisco advises checking that T.38 is configured globally and on both the incoming and outgoing dial-peers, then using debug ccsip to see why SIP rejected the re-INVITE. in context
• Cisco Named Signaling Events (NSE) fax switchover is Cisco-proprietary and cannot be used toward third-party SIP providers; standards-based (protocol-based) T.38 switchover must be used instead. in context
• A T.38 re-INVITE carries an m=image ... udptl t38 media line with attributes such as T38FaxVersion, T38FaxRateManagement (transferredTCF), T38FaxMaxBuffer, T38FaxMaxDatagram and T38FaxUdpEC (t38UDPRedundancy). in context
• T.38 version 3 (Super G3 speeds) is supported on Cisco IOS from release 15.1(1)T onward. in context
• Cisco's 2013 CUBE third-party fax guidelines state that Verizon, although claiming T.38 over SIP support, never initiates a voice-to-T.38 switchover when it is the terminating gateway. in context
• Cisco says the fax transport method must be consistent end to end across the originating gateway CUBE and terminating gateway path. in context
• For third-party interoperability Cisco recommends configuring CUBE with fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback none with dial-peer configuration taking precedence over global settings. in context
• Cisco states that NSE-based fax switchover is Cisco-proprietary so CUBE fax interworking with third-party equipment must use standards-based T.38 relay or protocol-based G.711 pass-through. in context
• Cisco's CUBE fax note says T.38 version 0 carries G3 fax speeds while T.38 version 3 supports Super G3 from Cisco IOS 15.1(1)T. in context
• In CUBE fax call flows the terminating gateway detects the V.21 preamble and triggers switchover to T.38 with a SIP ReINVITE (or H.323 RequestMode) which CUBE must permit. in context

Cite this source record

APA

WarmTransfer. (2013, August 14). CUBE Third-Party Interoperability Fax Guidelines. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-technote-116280-cube-fax-interop

BibTeX

@misc{warmtransfer-cisco-technote-116280-cube-fax-interop,
  title  = {CUBE Third-Party Interoperability Fax Guidelines},
  author = {{WarmTransfer}},
  year   = {2013},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-technote-116280-cube-fax-interop},
  note   = {Cisco, accessed 2026-09-24}
}