External trunk settings

Publisher

Genesys

URL

https://help.genesys.cloud/articles/external-trunk-settings/

Published

unknown

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

Genesys Resource Center terms; no-redistribution; short excerpts and locators only

Source notes citing this source

• If Release Link Transfer stays off, a transfer from Genesys Cloud back to a Unified CM extension is likely placed as a new outbound call that Genesys keeps bridged, so the call uses two trunk legs through CUBE. inferred in context
• The external trunk setting Enable Release Link Transfer turns on the outbound REFER method. in context
• IP addresses entered in a trunk's SIP Servers or Proxies list are added to the trunk's SIP Access Control allow list automatically. in context
• The external trunk setting Enable Take Back and Transfer turns on the inbound REFER method. in context
• The external trunk Media section sets a Preferred Codec List (g722, g729, PCMA, PCMU, opus) and an SRTP Cipher Suite List. DTMF Method can be RTP Events, In-band Audio or None. in context
• The external trunk's User to User Information settings are a UUI Passthrough switch, a header type (x-UserToUser, User-To-User or User-To-User PD Attribute), an encoding format (hex or ascii) and a two-digit hexadecimal protocol discriminator. in context
• Genesys Cloud external (BYOC) trunks offer three DTMF methods: RTP Events (default, RFC 2833/4733), In-band Audio, and None. in context
• The Genesys Cloud external trunk DTMF Payload setting accepts 96-127, defaults to 101, and applies only when the DTMF Method is RTP Events. in context
• In external trunk SIP Access Control, a subnet larger than /15 cannot be configured. in context
• The external trunk codec list can include audio/g722, audio/g729, audio/PCMA (G.711 A-law), audio/PCMU (G.711 mu-law) and audio/opus. in context
• External trunk protocol diagnostics do not capture SIP OPTIONS, REGISTER, SUBSCRIBE or NOTIFY messages. in context
• External trunks offer three DTMF methods, one of which is RTP Events: out-of-band DTMF carried in the RTP stream as defined in RFC 2833 and RFC 4733. in context
• If the PCI DSS setting is enabled for the organization, media capture cannot be enabled on a trunk; Genesys warns that media capture records everything entered, including Secure IVR input. in context
• Genesys warns against enabling PBX passthrough on trunks with PSTN access because it creates a high risk of toll fraud; allowing all addresses in SIP Access Control is also flagged as a security risk. in context
• On Premises External SIP trunks, retryable reason codes default to 500-599, and the default retryable cause codes include 1-5, 25, 27, 28, 31, 34, 38, 41, 42, 44, 46, 62, 63, 79, 91, 96, 97, 99, 100 and 103. in context
• External trunk media settings offer six SRTP cipher suites, including AES_CM_128_HMAC_SHA1_32, AES_CM_128_HMAC_SHA1_80 and AES_CM_256 variants. in context
• The external trunk transport protocol can be UDP, TCP or TLS. in context
• Genesys Cloud has three external trunk types: BYOC Carrier and BYOC PBX for BYOC Cloud, and Premises External SIP for BYOC Premises. in context
• Genesys documents that allowing all addresses in a trunk's SIP access control is a security risk. in context
• The Release Link Transfer trunk setting enables outbound SIP REFER and only affects an Architect call flow using the Transfer to Number action to transfer an external party to another external party. in context
• For Release Link Transfer the inbound call must arrive on the same trunk on which the outbound transfer is requested, and the setting cannot be combined with TCP Connection Timeout. in context
• The Take Back and Transfer trunk setting enables the inbound SIP REFER method so the external party can transfer an active call with a Genesys Cloud agent to another external party. in context
• Genesys Cloud external trunk preferred codec options are g722, g729, PCMA, PCMU and opus. in context

Cite this source record

APA

WarmTransfer. (2026, September 24). External trunk settings. WarmTransfer. https://warmtransfer.net/knowledge/sources/genesys-rc-external-trunk-settings

BibTeX

@misc{warmtransfer-genesys-rc-external-trunk-settings,
  title  = {External trunk settings},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/genesys-rc-external-trunk-settings},
  note   = {Genesys, accessed 2026-09-24}
}