On data calls between a data module and an analog-data endpoint, Return-to-Voice releases the modem and returns it to the pool. The telephone user connects to the analog-data endpoint.

For traffic purposes, the system accumulates data on modem-pooling calls separate from voice calls. Measurements on the pools also accumulate.

Modem Pooling is unrestricted. Queuing for modems is not provided, although calls queued on a hunt group retain reserved modems.

Avoid mixing modems from different vendors within a combined pool because such modems might differ in transmission characteristics.

Each data call that uses Modem Pooling uses four time slots (not just two). As a result, heavy usage of Modem Pooling could affect TDM bus-blocking characteristics.

Tandem switches or servers do not insert a pooled modem. The originating and terminating servers or switches insert a pooled modem.