Microsoft Lync with Enterprise Voice provides a full standalone VoIP solution that can replace the traditional PBX or enhance it. However, voice configuration in Lync is neither simple nor exactly intuitive as several elements such as Dial Plans, PSTN usages, Voice Policies, and Routes are involved. The availability of public documentation on the subject is large, however, often resulting in a challenging and confusing experience for the less experienced user.
Enterprise Voice is Microsoft's wording for Lync interoperability with PSTN voice.
Specifically to dial plans, routes, and trunk translation rules, you will also need good knowledge of Regular Expressions (