SIP 603+ FAQ

Publisher

Bandwidth Inc.

URL

https://www.bandwidth.com/support/en/articles/13778049-sip-603-faq

Published

2026-08-18

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

Bandwidth proprietary; no-redistribution; short excerpts and locators only

Source notes citing this source

• Bandwidth documents the 603+ Reason header as SIP cause 603 with a text parameter carrying a version value, the blocking party's identity, and a redress contact given as a URL, telephone number or email. in context
• Bandwidth states that from March 2026 it applies no code remapping, no retries or route advance, and header integrity to SIP 603 responses, passing reason phrases and Reason headers through transparently when their syntax is valid. in context

Cite this source record

APA

WarmTransfer. (2026, August 18). SIP 603+ FAQ. WarmTransfer. https://warmtransfer.net/knowledge/sources/bandwidth-help-sip-603-plus-faq

BibTeX

@misc{warmtransfer-bandwidth-help-sip-603-plus-faq,
  title  = {SIP 603+ FAQ},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/bandwidth-help-sip-603-plus-faq},
  note   = {Bandwidth Inc., accessed 2026-09-24}
}