Cisco Cisco Expressway Maintenance Manual
Call Types and Licensing
This section describes the different call types recognized by the Expressway and how they are licensed.
Call Types
The Expressway distinguishes between the following 2 types of call:
■
Unified CM remote sessions: these are "mobile and remote access" calls i.e.video or audio calls from
devices located outside the enterprise that are routed via the Expressway firewall traversal solution to
endpoints registered to Unified CM. These calls do not require rich media session licenses, although they do
contribute to overall load.
devices located outside the enterprise that are routed via the Expressway firewall traversal solution to
endpoints registered to Unified CM. These calls do not require rich media session licenses, although they do
contribute to overall load.
■
Rich media sessions: these calls consume rich media session licenses and consist of every other type of
video or audio call that is routed through the Expressway. This includes business-to-business calls, B2BUA
calls, and interworked or gatewayed calls to third-party solutions. The Expressway may take the media
(traversal) or just the signaling (non-traversal).
video or audio call that is routed through the Expressway. This includes business-to-business calls, B2BUA
calls, and interworked or gatewayed calls to third-party solutions. The Expressway may take the media
(traversal) or just the signaling (non-traversal).
Audio-only SIP traversal calls are treated distinctly from video SIP traversal calls. Each rich media session
license allows either 1 video call or 2 audio-only SIP traversal calls. Hence, a 100 rich media session license
would allow, for example, 90 video and 20 SIP audio-only simultaneous calls. Any other audio-only call (non-
traversal, H.323 or interworked) will consume a rich media session license.
license allows either 1 video call or 2 audio-only SIP traversal calls. Hence, a 100 rich media session license
would allow, for example, 90 video and 20 SIP audio-only simultaneous calls. Any other audio-only call (non-
traversal, H.323 or interworked) will consume a rich media session license.
Note that:
■
Expressway defines an "audio-only" SIP call as one that was negotiated with a single “m=” line in the SDP.
Thus, for example, if a person makes a “telephone” call but the SIP UA includes an additional m= line in the
SDP, the call will consume a video call license.
Thus, for example, if a person makes a “telephone” call but the SIP UA includes an additional m= line in the
SDP, the call will consume a video call license.
■
While an "audio-only" SIP call is being established, it is treated (licensed) as a video call. It only becomes
licensed as "audio-only" when the call setup has completed. This means that if your system approaches its
maximum licensed limit, you may be unable to connect some "audio-only" calls if they are made
simultaneously.
licensed as "audio-only" when the call setup has completed. This means that if your system approaches its
maximum licensed limit, you may be unable to connect some "audio-only" calls if they are made
simultaneously.
■
The Expressway does not support midcall license optimization.
License Bypass for Calls to Collaboration Meeting Rooms (CMRs)
The Expressway no longer requires rich media session licenses for calls to and from cloud-based CMRs. This includes
SIP calls between Collaboration Cloud and the CMR Hybrid solution.
SIP calls between Collaboration Cloud and the CMR Hybrid solution.
Note:
This only applies when the dialed string does not need transformation on the Expressway (for example,
user@sitename.webex.com).
Although untransformed SIP calls to cloud-based CMRs do not consume licenses, they do consume resources and
may not progress if the Expressway is at full capacity.
may not progress if the Expressway is at full capacity.
There is no license bypass for CMR Premises calls. H.323 calls to cloud-based CMRs still consume licenses.
What are Traversal Calls?
A traversal call is any call passing through the Expressway that includes both the signaling (information about the call)
and media (voice and video). The only other type of call is a non-traversal call, where the signaling passes through
the Expressway but the media goes directly between the endpoints (or between one endpoint and another system in
the call route).
and media (voice and video). The only other type of call is a non-traversal call, where the signaling passes through
the Expressway but the media goes directly between the endpoints (or between one endpoint and another system in
the call route).
A call is “traversal” or “non-traversal” from the point of view of the Expressway through which it is being routed at the
time. Traversal calls use more resource than non-traversal calls.
time. Traversal calls use more resource than non-traversal calls.
The following types of calls require the Expressway to take the media. They are classified as traversal calls and
always pass through the Traversal Subzone:
always pass through the Traversal Subzone:
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Cisco Expressway Administrator Guide
Reference Material