Multiple additional SIP domains - certificate and DNS requirements

Question

We've setup Lync 2010 Enterprise in our organisation and have successfully enabled a couple of thousand users.
This is working successfully internally, externally and through Lync Mobile.
However, we've only enabled users who are using the main company domain for SMTP and SIP addresses aaaaa_group.com (so all nice and easy so far!)
In other words, user A has a primary SMTP and SIP address of
UserA@aaaaa_group.com
However, due to numerous mergers and acquisitions over the years, we have quite a lot of users who have other primary SMTP addresses e.g. bbbbb_co.uk, ccccc_company.com, ddddd_ltd.co.uk, de.ccccc_company.com etc etc
There must be in excess of 40 to 50
of these other domains in use as primary SMTP addresses.
(Nearly all
these users have secondary SMTP addresses of aaaaa_group.com).
I have been told to approach this from a best practices point of view and give all users a SIP address that matches their primary SMTP address and calculate how much it will cost to buy certificates to cover enabling every user for Lync on all these domains.
I know from reading that wilcard certificates are considered to be a bad thing generally with Lync, especially if using Lync Mobility as the phone Lync clients don't accept them. 
Wilcard certificates aside, what are the names that will I need to add to my SAN certificates?  Presumably sip.domain.com, access.domain.com, meet.domain.com, dialin.domain.com, edge.domain.com, autodiscover.domain.com, lyncdiscover.domain.com
The potential cost of all these names is frankly getting pretty scary considering we currently use Verisign for all our cert requirements, and they charge like a wounded bull.  However, I still need to report back with a cost of doing this, no matter
what it is.
Any thoughts/comments would be very welcome. :-)

Answer 1

Actually the Mobility clients for mobile devices (cell phones, tablets) DO support wildcard entries in the certificates, it's the Lync Phone Edition client (desktop handset devices) which does not work with wildcards.  So you may be able to use wildcards,
but do plenty of research on how to approach this.  Here are some articles to get started:
http://blog.schertz.name/2011/02/wildcard-certificates-in-lync-server/
http://blog.schertz.name/2011/02/lync-phone-edition-incompatible-wildcard-certificates/
That said, if you decide to skip the wildcard approach then you do NOT need to add additional entries for ALL FQDN types, only some.
For both the Edge Server external certificate and any internal Front End certificate you'll need to add the 'sip' FQDN for every domain to the SAN field.
sip.domain1.com, sip.domain2.com, sip.domain3.com, etc
The Front End certificate will also need the lyncdiscover and lyncdiscoverinternal
FQDNs, and the Reverse Proxy certificate will require the lyncdiscover
FQDNs.
For Exchange Server you'll need to an autodiscover.domainX.com record as well, although this can also be covered by the wildcard entry.  The remainder of names (web conferencing, external web services, dialin, meet, etc.) can all remain in the primary
SIP domain only as these FQDNs will be passed in-band to the clients after they have successfully signed-in to Lync.  Unless you need users to all user their own domain names for the SimpleURLs (which it doesn't not sound like in your scenario) then you'd
have to add all those as well.
So if you are not supporting any Lync Phone Edition devices I would try going with the wildcard route first to see how well things work.  And even if you do have some of those devices you could simply add the 40-50
sip.domain.com FQDNs to both the FE and Edge certificate but still use a wildcard entry for the mobility clients, SimpleURls, etc.  Just make sure that the certificates Common Name (e.g. Subject Name) is NOT the wildcard entry, use the primary
domain name entry in the CN and then place the wildcard entries in the SAN field.  It is also best practice to duplicate the CN as a SAN field entry for the widest range of support by all clients.
For example:
Edge Server external certificate
Common Name: sip.domain1.com
Subject Alternative Name: sip.domain1.com, *.domain1.com, *.domain2.com, *.domain3.com, *.domain4.com,
etc...
Jeff Schertz | Microsoft Solutions Architect - Polycom | Lync MVP