SDP transparency profiles contain a set of rules for declarative SDP attributes that allow the system to pass through declarative attributes that are not natively supported by Cisco Unified Communications Manager from the ingress to the egress call leg. Without an SDP transparency profile, Cisco Unified Communications Manager drops non-supported SDP attributes.
You can configure SDP transparency profiles with multiple rules and apply them to SIP devices or trunks via the SIP profile. In order for the SDP transparency profile to be applied, both call legs must be SIP. You can configure the following types of rules for SDP attributes:
Property—If a rule is configured for a property attribute, Cisco Unified Communications Manager passes through the SDP attribute unless the attribute has a value.
Any Value—If a rule is configured for any value, the SDP attribute gets passed through so long as it has a value that consists of at least one non-white space character.
Value From List—If a rule is configured using this option, the SDP attribute gets passed through so long as it matches one of the specified values. You can configure up to five possible values
SDP Transparency Profile Restrictions
The following restrictions apply to SDP transparency profiles. If any of these situations occur on the egress call leg, Cisco Unified Communications Manager will not pass through the declarative SDP attribute:
One or more Media Termination Points (MTPs) or Trusted Relay Points (TRPs) that do not support passthrough are allocated
The Media Termination Point Required check box is checked for the SIP trunk
A transcoder is being used
RSVP is being used
The ingress call leg is using Delayed Offer while the egress call leg is using Early Offer
The media line has been rejected (port=0)
Either call leg is using a protocol other than SIP
SDP Transparency Profile Prerequisites
If you plan to deploy any third-party SIP products, make sure that you understand how the products implement the Session Description Protocol (SDP).
Configure SDP Transparency Profile
Configure an SDP transparency profile with a set of rules for declarative SDP attributes that are not natively supported by Cisco Unified Communications Manager. If the SDP transparency profile is applied to a SIP device, Cisco Unified Communications Manager passes the SDP attribute from the ingress to the egress call leg.
From Cisco Unified CM Administration, choose Device > Device Settings > SDP Transparency Profile.
Click Add New.
Enter a Name and Description.
In the Attribute Information pane, create the rules for the SDP attributes that you want to pass through:
To pass through a property attribute, enter the attribute in the Name text box (for example, a=recvonly) and from the Type drop-down list box, select Property.
To pass through a value attribute, enter the attribute in the Name text box (for example, a=rtpmap), and select Any Value from the Type drop-down list box.
To pass through a value attribute with any of up to five values, enter the attribute in the Name field (for example, a=rtpmap) and select Any Value from the Type drop-down list box. In the resulting Value text box, enter the value of the attribute. You can click + to add up to five possible values for this attribute.
Click the (+) to create new lines where you can enter additional SDP attributes for this transparency profile.