 to do and the call will complete successfully. There are regions in the world where such a call would constitute an illegal call, violating country regulations regardless of whether you can technically route and complete the call along that path. When considering aggregated SIP trunking and your business spans country or regional boundaries, ensure that you are familiar with the regulations in the areas where you oper- ate to determine what a legal call path is. Areas of careful evaluation include India and the Middle-Eastern countries but might also be applicable in other parts of the world, or in some cases between regions of the same country. Tip Become familiar with regulations that govern which call paths are considered legal. If you prefer not to invest in this analysis, plan to have a largely distributed SIP trunk model where you have a SIP trunk in at least each region where your business operates. If you do not aggregate calls at all-that is, if you implement a fully distributed SIP trunk model- this consideration becomes a nonissue. Containing Oversubscription One of the key attractions of a centralized SIP trunk is that you can consolidate the inherent oversubscription many TDM PSTN connections have because the only physical connectivity choice is a T1/E1 trunk even though the site might require, say, only 12 simultaneous calls. When you consider this benefit to underpin your cost evaluation to justify a central SIP trunk model, ensure that you truly understand your traffic patterns. Today, if that local remote site that ostensibly requires only 12 calls but has a full T1, occasionally bursts to 20 calls, there is no impact on your network and no customers or employees complain. However, if you provision a central SIP trunk for only 12 calls and the 13th call of the burst is rejected because of Call Admission Control (CAC) on the SIP trunk, those employees are now impacted and will either complain or fail to conduct the business they have to complete. Containing oversubscription also does not necessar