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Collaboration, Voice & AV · Advanced

Early Offer (EO)

A SIP call flow in which the initial INVITE contains the SDP offer, required by most service provider SIP trunks.

Definition

With early offer the caller describes its media in the INVITE, and the callee answers in a provisional or final response. Many carriers require early offer, but CUCM SIP trunks default to delayed offer; CUCM can send early offer by enabling Early Offer support on the SIP profile, which may insert an MTP when the calling device's media details are unknown. CUBE can also convert delayed offer to early offer.

Example

voice service voip / sip / early-offer forced makes CUBE send early offer to the ITSP even when CUCM sends delayed offer.

Exam tip

When a carrier rejects calls from CUCM because the INVITE has no SDP, fix it with Early Offer on the SIP profile or early-offer forced on CUBE.

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