Mino – The UC Guy

Microsoft Unified Communications Blog

Archive for September, 2010

OCS / Lync Server Normalization Rules

Posted by Mino on September 30, 2010

This is a very good post by Jonathan McKinney about Normalization Rules , what I loved in it is the simplicity of explanation. Please appreciate this post young folks , we learnt it the hard way by practice and projects because there was no one to explain it to us this way 🙂

Thanks Jonathan https://www.t2mdev.com/jonmck/Lists/Posts/Post.aspx?ID=6

When normalization rules were first explained to me in an Office Communications Server 2007 training class, I left thoroughly confused.

I spent quite a lot of time trying to understand how normalization rules work. First, I found that normalization rules are .Net Expressions. A quick search of the Internet for .Net Expression primers and help guides did not help with understanding how they worked.

I finally found a piece of software called RegEx Designer that allowed me to see what is happening in a .Net expression and more importantly a normalization rule.

Let’s start with why we need telephone numbers (straight from the IETF/ITU standards).

  1. A telephone number is a string of decimal digits that uniquely indicates the network termination point.

  2. The number contains the information necessary to route the call to the termination point.

A Normalization Rule modifies the user input and presents a fully routable telephone number that can be used by Office Communications Server (OCS) / Lync Server and the PSTN to delivery a voice call to the intended termination point. To OCS / Lync Server, your telephone number is effectively meaningless if it is not presented in E.164 format.

Humans are inconsistent, especially with how we write phone numbers down. People use parens, dashes, dots, and spaces for example. Users in a business might only know a 4 digit extension to call another employee. Normalization Rules help the humans enter the phone number in the format they are used to and then translate that to the pattern that OCS / Lync Server is expecting.

There are three main processes happening when a normalization rule is used.

  1. Does the Phone Pattern Regular Expression match the input?

  2. What is captured in the Phone Pattern Regular Expression to be used by the Translation Pattern Regular Expression?

  3. What is the Translated number?

Example Normalization Rule

Phone Pattern Regular Expression: ^(2\d\d\d)$
Translation Pattern Regular Expression: +1425555$1

The "^" specifies that the match must occur at the beginning of the string.

Anything between parens is captured into a group. If there are more than one set of parens then there are multiple groups.

Any letter that is after "\" is considered a language element and has a special function. For example \d is a single digit wildcard. \D is a single character wild card.

"$" Specifies that the match must occur at the end of the string.

In the above example we are matching against any 4 digit number that starts with a 2. We are capturing the 2 into group 1 plus any other 3 digits that follow. If a number is 5 digits it will not match. If a number starts with any other number than 2 it will not match.

Now that we have captured group 1 we can take a look at the Translated Pattern Regular Expression

Phone Pattern Regular Expression: ^(2\d\d\d)$
Translation Pattern Regular Expression: +1425555$1

The +1425555 are absolute digits and will be inserted before the captured digits in group 1 "$1". Each group is represented by a $ and a digit for the order in which they were captured. The second group captured would have a "$2" in the Translation Pattern Regular Expression.

If we entered 2345 then the translated pattern would be +1425552345.

What if we wanted to match against 5 digits and only capture 4 for example?

Phone Pattern Regular Expression: ^6(\d\d\d\d)$
Translation Pattern Regular Expression: +1425555$1

The above rule would match any 5 digit number that started with a 6. But, because the 6 is not within the Parens we will not capture the 6 into group 1.

If we entered 62345 then the translated pattern would be +1425552345.

Is there an easier way to specify multiple digits rather than writing\d\d\d\d?

Phone Pattern Regular Expression: ^6(\d\d\d\d)$
Translation Pattern Regular Expression: +1425555$1

is the same as

Phone Pattern Regular Expression: ^6(\d{4})$
Translation Pattern Regular Expression: +1425555$1

The {x} specifies the number of matches for the preceding Language Element. In this case we are looking for 4 digits. If I specified \D{4} then it would be 4 characters.

If we entered 62345 then the translated pattern would be +1425552345.

What does a normalization rule look like capturing multiple groups of numbers?

Phone Pattern Regular Expression: ^(\d{3})(\d{4})$
Translation Pattern Regular Expression: +1425$1$2

In the above Phone Pattern there are two sets of parens. Each set of parens captures into a different group. The first three digits are captured into group 1 "$1" and the next 4 digits are captured into group 2 "$2".

In the Translation Pattern we use $1 and $2 after the +1425.

If we entered 5552345 then the translated pattern would be +1425552345.

What if we wanted to handle dashes, spaces, dots, and whatever else users dream up?

Phone Pattern Regular Expression: ^(\d{3})\D(\d{3})\D(\d{4})$
Translation Pattern Regular Expression: +1$1$2$3

In the Phone Pattern Regular Expression we are matching for 3 digits, then a single character. Then another three digits, and a single character. Then a final four digits. Since the \D is not within the parens we match against it, but are not capturing it. The result is the Translation Pattern has no dashes, dots, spaces, or any other character the user can dream up.

If we entered 425-555-2345 or 425.555.2345 then the translated pattern would be +1425552345.

Why do you use \D instead of [\s()\-\./] ?

Simple. It does the same thing and more! \D will match any non-digit. [\s()\-\./] will only match space, parens, dash or dots.

Is there a way to do optional matches?

Phone Pattern Regular Expression: ^9?(\d{3})\D(\d{3})\D(\d{4})$
Translation Pattern Regular Expression: +1$1$2$3

In the Phone Pattern Regular Expression above we start of with a "9?". This means the expression will match if there is a 9 or not a 9. The key is using the question mark after the number (or character). This is handy if you want to be allow users to still dial a 9 like they used to on a PBX. They can type it in or not, we simply don’t care because it is optional and we are not capturing that digit into a group.

If we entered 9425-555-2345 or 425-555-2345 then the translated pattern would be +1425552345.

How would I do a wild card for any number of characters/digits?

Phone Pattern Regular Expression: ^\D*(\d{3})\D*(\d{3})\D*(\d{4})$
Translation Pattern Regular Expression: +1$1$2$3

The above Phone Pattern Regular Expression will look for any amount of characters until it matches against 3 digits. Then any amount of characters until it matches against another 3 digits. Then a match against the last four digits.

The benefit of this is that we can handle "(425) 555-1234" or "425-555-1234" or "4255551234" and to be honest we can handle this too "Your grandma 425 has white 555 hair 1234". All the examples would be translated to +14255551234

How about logical OR?

Phone Pattern Regular Expression: ^\D*(303|720)\D*(\d{3})\D*(\d{4})$
Translation Pattern Regular Expression: +1$1$2$3

A logical OR is very handy if you need to handle multiple area codes, or NXXs (the second set of 3 digits for non-voice people). The pipe sign is what does the logical OR within the parens. The above Phone Pattern Regular Expression would look to match the first three digits to 303 or 720, but not both.

If we entered 303-555-2345 or (720) 555-2345 then the translated pattern would be either +1303552345 or +17205552345.

Conclusion

In my experience the above examples will help with 90% of the needs for Normalization Rules. There are much more complicated Normalization Rules that could be written, but I’ll leave that to another post. If you want to play around with Normalization Rules I strongly encourage downloading RegEx Designer so that you can visibly see how Normalization Rules work.

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Posted in Uncategorized | 6 Comments »

How to allow domain users to connect to Lync 2010 or OCS 2007 from Clients running on non-domain computers

Posted by Mino on September 15, 2010

I had a situation in our company where we have exceptional few users who got Domain credentials but they are working on Computers that are not joined to the domain.

However these computers run over the LAN or WAN, can communicate with the internal DNS and got the certificate chain of the CA imported to them and they use DOMAIN\UID and password credentials to login to mail , MOSS and everything is working fine.

When I installed the OCS 2007 R2 client on their machines and tried to login with the same behavior as mail using DOMAIN\UID , I was not able to log in and I received the below event log warning:

"Communicator was unable to authenticate because an authenticating authority was not reachable.”
Resolution:
The server may be asking for Kerberos authentication and Communicator is not able to find the Kerberos Domain Controller in order to generate credentials and authenticate.  The network administrator will need to change the configuration on the server to utilize only NTLM authentication before Communicator can login from this location properly, or connectivity will need to be made available to an authenticating authority"

 

also as for testing I removed the OCS 2007 R2 client and installed the new Lync RC client on the same machine , I know it is not supported scenario but I was just testing it. Now the user was able to login but it disconnects after 10 seconds then reconnects again , it keep in this loop. I also found the same warning in the event log.

I know why this is happening and I know it would have been solved from the beginning if i forced the OCS to use NTLM only rather than Kerberos but this was not something i can force.

So in the end the Solution was this problem was simple :

Ensure that the users when singing in to communicator 2007 or Lync 2010 to include the ".local" in the domain.local\username part of the authentication and not DOMAIN\username.

Posted in Common Errors, communicator client, Lync 2010 Client | Tagged: , , , | 3 Comments »

Microsoft Lync Server 2010 Media Bypass

Posted by Mino on September 14, 2010

What is it?
  • Media Bypass allows for Lync clients to communicate directly with a qualified PSTN voice gateway or qualified IP-PBX without traversing the Mediation server for media transcoding

  • When clients use Media Bypass, the Lync client uses the G.711 codec over SRTP

What are the benefits?
  • Greatly simplifies topology
    • Allows for Mediation server to collocate with Front End server or SBA because of low CPU intensity
    • Greatly reduces the amount of servers needed in deployment resulting in lower TCO
  • Optimizes media flow and quality
    • Eliminates unnecessary hops and potential points of failure
    • Saves WAN bandwidth
    • Improves voice quality with use of G.711 codec

However to enable Media Bypass ,you must ensure that either the Media Gateway ( SBA ) or the IP-PBX does support the Media Bypass feature.

Below are some different scenarios for the Media bypass between 2 sites:

First Scenario :

In this scenario the Client in the main data center dials a PSTN number, so the client communicates directly with the gateway using G.711 codec without the need to used the mediation for transcoding from RTaudio to G.711 Codec.

MB1

Second Scenario :

In this scenario the client is located in the branch site where there is no Lync Servers installed , when the client places a PSTN call it communicates directly with the IP-PBX over G.711 without the need for getting back to the Data Center pool mediation for transcoding. However this scenario is only applicable if your IP-PBX does support the new Media Bypass feature.

MB2

Third Scenario :

In this scenario we have two clients placing the call , one from the Data Center and the second is in Branch site. you will typically have this case in the international sites where you want to enable the least cost routing for international numbers. Lets say the Main Data Center is in US and the branch Site is in Egypt , and both Clients will dial the same number which is a US number.

So the first client who is in the US data center will communicate to the mediation server directly over G.711 , then the mediation will place the call through the Hosted SIP trunk to the PSTN also over G.711 since there is no local PBX available in the Data Center.

The Second Client who is in the Egypt branch site will dial the US number , the client will communication with the Mediation server place in the US Data center over RT Audio then the mediation will talk to the PSTN over G.711. In this second scenario we used RT Audio because it has got lots of features over the G.711 which consumes more bandwidth  , RT Audio gives much better quality over WAN due to correction mechanisms and the ability to overcome lost packets.

MB3

Forth Scenario :

In this scenario we have the same case like the last one , however we have also enabled Call Admission Control ( CAC ) which is a new great feature in Lync Server 2010. It allows call control over WAN to assure the accepted number of call over the allocated bandwidth and to refuse any extra calls over the allowed limit . What makes this CAC feature great also is not only to control calls over the WAN , but also to give alternate route for calls over the PSTN rather than using the WAN.

Ok let me explain it , the Client in the Egypt branch site is placing an international call to US number , so the client tries to place the call through the mediation placed in the US data center over the WAN , however due to WAN full usage and the CAC control ( call admission control ) so the call is not allowed to be placed over the WAN , however in spite of dropping the call we find that the client is redirected with alternate route to his local GW to place the call as international number from his PSTN gateway.

MB4

Fifth Scenario :

In this scenario the Client who is placed in the branch site places a call to a PBX legacy endpoint which is placed in the main site data center , this endpoint is connected to the IP PBX where this IP-PBX does not yet support direct Media bypass.

So the Client communicates over the WAN to the mediation server over RT Audio , then the call is routed after transcoding from the Mediation to the IP-PBX over G.711 , and finally the IP-PBX sends the call to the end point directly over G.711.

MB5

Posted in Lync 2010 Client | Tagged: , , , , , | 6 Comments »