Microsoft Lync Server 2010 : Enterprise Voice - Voice Routing (part 2) - Routes, PSTN Usages, Trunk Configuration

4. Routes

Routes are used in Lync Server to direct calls through a specified gateway or a set of gateways. Routes are processed after numbers are normalized based on a dial plan and determine which gateway will place a call. Creating a new route has the following options:

• Starting digits for numbers that you want to allow— Routes are based on the beginning of the digit string, including the addition (+) symbol. Routes are matched based on a top-down matching algorithm, so the most specific routes should be highest in the route order.

• Exceptions— In some cases, using route priority might be difficult or some patterns should be excluded from traversing a specific gateway. The Exceptions option allows an administrator to exclude strings that would otherwise match the route.

• Suppress caller ID— This option enables an administrator to prevent the caller’s actual caller ID from being passed along on the route. An alternative caller ID must be entered that is typically a main or generic phone number. A limitation here is this cannot be variable based on the calling party ID. Instead, only a single phone number displayed for all outbound calls can be used.

• Associated gateways— A list of gateways that calls matching this route and can be used for outbound calls. Calls will be placed in a round-robin fashion if multiple gateways are associated.

• Associated PSTN usages— The PSTN usages allowed to use this route. Usages are associated with users through voice policies.

To create a new route, use the following steps:

5. PSTN Usages

PSTN usage records are associated with routes and voice policies to provide a way to control which users are allowed to use specific routes. Voice policies are applied to users, which contain a list of PSTN usages. If a user dials a number that matches a route with one of those PSTN usages, the call will be placed. If not, the user will be unable to make the call.

To create a new PSTN usage record, use the following steps:

6. Trunk Configuration

A trunk is a logical connection between the Mediation Server role and a PBX, PSTN gateway, or Internet Telephony Service Provider. The trunk settings apply to any gateway the site or pool is associated with, so if these settings vary across gateways, a new pool might be required for each unique set. Creating a new trunk configuration has the following options:

• Scope— A trunk can either be scoped so that it applies to entire Lync Server site or it can be restricted to only a specific Front End pool. A global trunk configuration also exists.

• Maximum early dialogs supported— This value is the number of forked responses the opposite end of the trunk can support in a single SIP INVITE that it sends to the Mediation Server.

• Encryption support level— Required means Secure Real-Time Transport Protocol (SRTP) must be used to encrypt the media traffic on the trunk, Optional means the Mediation Server attempts to use encryption if the gateway supports it, and Not Supported means the media traffic is not encrypted on the trunk.

• Enable media bypass— Use if endpoints are allowed to communicate directly with the opposite end of the trunk. This configuration is highly recommended to reduce processing on the Mediation Server.

• Centralized media processing— Use if the signaling and media traffic for this trunk terminate at the same IP address. If using Media Bypass is enabled, this option must also be selected.

• Enable refer support— Use if the trunk endpoint supports receiving SIP REFER requests from the Mediation Server.

To create a new trunk, complete the following steps:

Alternatively, the Lync Server Management Shell can be used to create a trunk configuration:

New-CSTrunkConfiguration –Identity <Name> -ConcentratedTopology
<$True|$False> -EnableBypass <$True|$False> -EnableReferSupport
<$True|$False> -MaxEarlyDialogs <$True|$False> -OutboundTranslationRulesList
<Collection of translation rules> -SRTPMode <Required|Optional|NotSupported>


					  

There are also a number of parameters configurable for a trunk that are not exposed in the Lync Control Panel. These parameters can be set using only the New-CSTrunkConfiguration or Set-CSTrunkConfiguration cmdlets:

• EnableMobileTrunkSupport— True or false value to indicate whether the trunk is a mobile carrier.

• EnableSessionTimer— True or false value to indicate if each session is timed to determine whether it is currently active or not.

• EnableSignalBoost— True or false value to indicate whether the opposite end of the SIP trunk should boost the audio volume of packets sent to Lync. This feature works only if the opposite end of the SIP trunk supports the feature.

• RemovePlusFromUri— True or false value to indicate whether the Lync server should remove the plus prefix (+) from URIs before sending them across this SIP trunk.

• RTCPActiveCalls— True or false value to indicate whether the trunk sends RTP Control Protocol packets for active calls.

• RTCPCallsOnHold— True or false value to indicate whether the trunk sends RTP Control Protocol packets for calls placed on hold.