Hi all,
Here are the configuration steps for a typical way to use the Audiocodes
Stand-Alone Survivability (SAS) Feature with sipXecs 4.0.
This feature can be useful for a branch office that has a local
Audiocodes Gateway, but uses a remote sipXecs server. In "Normal" mode
the Audiocodes Gateway transparently proxies the SIP messages between
the phones and sipXecs server. It also sends periodic "keepalive"
messages to the sipXecs server in order to confirm connectivity. If
connectivity to the sipXecs server is lost then the Audiocodes Gateway
goes into "Emergency" mode allowing branch phones to make calls out the
PSTN and to each other. Once connectivity is restored, the Audiocodes
Gateway switches back to "Normal" mode.
The instructions below are based on the results of my testing with an
Audiocodes FXO MP-118 (5.6 firmware), a Polycom SoundPoint IP 430, and
an LG-Nortel 6830.
Configuration Steps:
1. sipXconfig Phone Profiles
To have a phone use SAS, configure its Outbound Proxy values as follows:
Address: The FQDN of the Audiocodes Gateway, e.g. gw.example.com
Port: 5080 (yes 5080, not 5060)
This forces the phone to send its all SIP messages through the
Audiocodes Gateway.
Phones that do not have a configurable Outbound Proxy cannot make use of
the Audiocodes SAS feature. (Well, at least not using these
instructions.)
Be aware that in sipXecs 4.0 the Polycom SoundPoint IP profiles by
default include per-Line Outbound Proxy values, found under "Lines" - X
- "Registration" (and "Show Advanced Settings".) The per-Line values
take precedence over the per-Phone values found on the "SIP Servers"
screen. You need to change the per-Line values.
The profile of course also needs to be re-generated and sent to the
phone.
2. sipXconfig Dial Plan
The Dial Plan must be constructed so that all digits dialed by the user
are passed to the Audiocodes Gateway. i.e. None of your PSTN rules can
have prefixes that are dropped before the call is sent to the gateway.
This means you cannot use the built-in "Local" or "Long Distance" rules,
and you will need to construct "Custom" rules instead. The "Emergency"
rule may be used, although you should test that it works in both Normal
and Emergency mode.
3. sipXconfig Audiocodes Gateway Profile
Only two changes need to be made to the Audiocodes Gateway Profile to
enable SAS:
First, navigate to "Proxy and Registration" and change the "Proxy
Keepalive Mode" setting to "Use OPTIONS".
Second, navigate to "Advanced Parameters" (and "Show Advanced Settings")
then the "Stand-Alone Survivability" section at the bottom, and check
the "Enable SAS" setting. (Note that the "SAS Local SIP UDP port" is
set to 5080, which you used in Step #1.)
As usual you will need to ensure the Primary DNS setting (under
"Network") and the PSTN Lines are both configured.
The profile of course also needs to be re-generated and loaded into the
Audiocodes Gateway.
4. Audiocodes Gateway IP -> Tel Destination Number Manipulation
After loading the profile into the Audiocodes Gateway there is some
configuration that must be done through the gateway's Web interface.
These settings are not currently available in the sipXconfig Audiocodes
Gateway Profile.
Navigate to "Protocol Configuration" - "Manipulation Tables" - "Dest
Number IP->Tel". (In pre-5.6 firmware this table is under "Protocol
Management" - "Manipulation Tables".)
Recall from Step #2 that our sipXecs Dial Plan passes all dialed digits
to the gateway. So, you must now configure the gateway to drop the
digits that you don't want sent to the PSTN. This way the PSTN calls
will work in Normal and Emergency mode, because in both cases it's the
gateway dropping the digits.
I won't repeat the Audiocodes documentation verbatim here. Instead I'll
describe the sipXecs Dial Plan used in my testing, and the corresponding
Audiocodes IP -> Tel number manipulation required to make it work.
The Audiocodes Gateway is connected to an analog line where dialing
"51111" or "63951111" will reach my actual desk phone.
sipXecs Dial Plan:
- built-in Emergency rule: Emergency number "51111", (Optional) PSTN
prefix "9".
- Custom "9-ThenAnyNumberOfDigits" rule: Dialed Number Prefix "9" and
"Any number of digits", Resulting Call Dial blank and append "Entire
Dialed Number"
- Custom "3-AndFourDigits" rule: Dialed Number Prefix "3" and "4
digits", Resulting Call Dial blank and append "Entire Dialed Number"
Audiocodes IP -> Tel number manipulation:
- For each entry the Source Prefix and Source IP are "*", and the
Number of Digits to Leave is blank.
- To cover the Emergency rule without the optional PSTN prefix:
Destination Prefix: 51111
Stripped Digits Number: 0
Prefix (Suffix) to Add: blank
- To cover the 9-ThenAnyNumberOfDigits rule, and the Emergency rule
with the optional PSTN prefix:
Destination Prefix: 9
Stripped Digits Number: 1
Prefix (Suffix) to Add: blank
- To cover the 3-AndFourDigits rule:
Destination Prefix: 3
Stripped Digits Number: 1
Prefix (Suffix) to Add: 5
Then in both Normal and Emergency mode, composing any of the following
dial strings will ring my actual desk phone:
- 51111 (Emergency rule)
- 951111 (Emergency rule, with optional PSTN prefix)
- 963951111 (9-ThenAnyNumberOfDigits rule)
- 31111 (3-AndFourDigits rule)
Unfortunately all configuration added through the Audiocodes gateway's
Web interface will be lost each time you reload the profile. Once
you've got your Audiocodes IP -> Tel number manipulation working, be
sure to write it down somewhere and re-program it whenever you reload a
new profile.
Limitation affecting Polycom SoundPoint IPs:
There is a known limitation affecting Polycom SoundPoint IP phones in
Emergency mode. The Audiocodes seems to have problems recognizing when
a Polycom is dialing another branch phones, and instead treats the digit
string as a PSTN call. This means Polycoms cannot dial other branch
phones in Emergency mode. This problem does not affect Normal mode.
The only known work-around is to dial the branch users through Speed
Dial buttons where the "Number" includes the SIP domain. e.g.
[email protected].
Please let me know if you have any questions or suggested improvements.
Thanks.
-Paul
[email protected]
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