You must assign different signaling groups in cyclical order for subsequent members of the trunk group. For example, if you have three signaling groups, such as 1, 2, and 3, assign the groups in the order 1, 2, 3, 1, 2, 3, 1, 2, 3, and so on for the subsequent members of the trunk group. This ensures that load balancing occurs amongst the different signaling groups.