Larger enterprises with more sophisticated designs/requirements should collaborate with their prospective suppliers to successfully figure out how to transition from PRI to SIP.
FREMONT, CA: As carriers push users to shift away from copper TDM-based services through price increases or abrupt sunset warnings, more clients are transitioning to SIP. PRI trunks can replace by SIP trunks on a business communications system. In several cases, providers making this transition require extensive planning. Whether the IP access/transport is shared or dedicated is another consideration. Organizations with enough capacity may add SIP trunks to an existing Internet or MPLS circuit. Other organizations keep their SIP trunks on separate IP access/transport that exclusively carries SIP traffic.
Architecture evaluation
Moving to SIP will necessitate changing the voice network's architecture. When firms with local PRIs serving particular sites shift to a centralized design, SIP trunks are delivered to select data centers and pooled as an enterprise resource. Centralization can increase efficiency. Also, the call paths required are (surprise) smaller than the traditional network's PRI call paths. Traffic studies assist in predicting future load. After seeing the genuine usage picture from portal statistics, organizations should consider throttling down call paths from their supplier.
Keep failover in mind
Failover capabilities vary by the provider if sending SIP trunks to many locations. Sometimes failover differs by access type. For instance, MPLS may provide enhanced failover capabilities over Internet use. IP access/transport should be sized based on the principal CODEC used. Provide failover scenarios where possible. Asking the supplier if active calls will drop, how many call pathways will be available at the remaining data center, and what level of redundancy/diversity is in quotes.
Count faxes
Moving fax to SIP can be challenging. If the firm still uses fax machines as analog stations over the PRI network, it should check the provider's commitment to supporting fax traffic over its SIP network. IP fax failures are more likely with high-page-count transmissions. The provider's engineer will set up fax traffic to use T.38 or G.711 and test before cutover.
Process porting orders
Porting DIDs from PRI provider to new SIP provider is a delicate ballet. If not, one of the carriers will reject the order to be fixed and resubmit it. For enterprises with many PRIs from many carriers, processing port orders take longer, and port dates may be delayed or missed. Porting requires time (20-30+ days per order), attention to detail, and current records (bills/CSRs).
