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Collaboration, Voice & AV · Advanced

Overlap Sending

Sending dialed digits one at a time or in groups to the next system instead of all at once in the initial setup message.

Definition

With overlap sending, a call is routed as soon as enough digits identify the destination and remaining digits are sent afterward, which suits variable-length numbering plans such as in parts of Europe. The alternative, en bloc sending, sends the complete number at once and is preferred by most SIP providers. CUCM supports overlap sending and receiving on ISDN gateways and SIP trunks with KPML or multiple INVITEs.

Example

A German PRI carrier accepts digits via overlap sending for variable-length extension numbers.

Exam tip

En bloc is the norm for SIP trunks; overlap sending appears mainly with ISDN and variable-length dial plans.

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