Cisco Cisco Expressway
Configuring Expressway Routing
Prerequisites
The Expressway-C must be configured with IP address, DNS and NTP information, and is accessible for management
via its web interface (see
via its web interface (see
).
Rich media session licenses must be installed.
Configuration Summary
The configuration on Expressway-C contains the following tasks:
■
Creating a transform to ensure a consistent URI format
■
Configuring a neighbor zone that contains the Unified CM
■
Configuring a search rule to route calls to that zone
■
Configuring a transform that converts number@<IP address of cucm> to number@exp.domain
■
Configuring a transform to convert other Unified CM-supplied domain variants to number@exp.domain
These tasks are explained in detail below.
Ensuring a Consistent URI Format
In this deployment scenario, users want to be able to route calls via the Expressway to other devices or endpoints (not
registered to Unified CM) that have a 4xxx extension number. Unified CM endpoints are to be dialed using a 3xxx
number. This dialing model can be supported by H.323 (if the endpoint registers the 4-digit E.164 alias), however, SIP
does not support dialing by numbers alone. If a number (without a domain appended) is dialed from a SIP endpoint the
endpoint will automatically append its own domain.
registered to Unified CM) that have a 4xxx extension number. Unified CM endpoints are to be dialed using a 3xxx
number. This dialing model can be supported by H.323 (if the endpoint registers the 4-digit E.164 alias), however, SIP
does not support dialing by numbers alone. If a number (without a domain appended) is dialed from a SIP endpoint the
endpoint will automatically append its own domain.
For consistency with both SIP and H.323 dialing, this deployment scenario always uses the URI form for routing calls
(that is, dialed_digits@domain). When the Expressway receives a call request, the dialed number:
(that is, dialed_digits@domain). When the Expressway receives a call request, the dialed number:
■
will contain the 4 digit extension number that identifies the specific endpoint to route to
■
may or may not include a domain (only included when a SIP endpoint is making the call)
Thus, a transform is needed to ensure that the dialed number is transformed into a consistent form, in this case to add
the domain (exp.domain) if required. To achieve this, a regex is used:
the domain (exp.domain) if required. To achieve this, a regex is used:
([^@]*)
transforms to
\1@exp.domain
(any dialed
information which does not contain a domain – does not contain an ‘@’ – has the ‘@exp.domain’ added.)
or alternatively search the internet for the term “Regular Expression”.
To create the transform:
1.
Go to Configuration > Dial plan > Transforms.
2.
Click New.
15
Cisco Expressway SIP Trunk to Unified CM Deployment Guide