The number of SS7 Links (connections) that are required is calculated on the number of SS7 Servers and the expected maximum call capacity. The smallest unit of SS7 communication is a Link. This is a single timeslot within an E1 or T1 trunk, and is capable of transferring data at 64 kbps. Based on a typical SS7 message structure and 40% utilization, a single Link can support up to 30 calls per second. For example, if 105 calls/second is required, 4 Links are required to handle the capacity.
The number of SS7 Servers will already be defined. If the redundancy method of two SS7 Servers is used, the calculated number of Links can be divided evenly between them. If the number of Links is an odd number, increase the Link count by one. As a 40% utilization is used in the calculation, this configuration can still function correctly with one SS7 Server failing.