We're looking to deploy Lync 2013 and use the following features:

Video Conferenceing, IM/Presence, and Desktop Sharing.  Number of employees that will be using these features is roughly 30.  Some of these employees are remote employees with laptops and VPN access.

What is the minimum amount of servers required for this setup?  Servers will be virtual servers running on VMWare 5.

It will really depend on a number of questions, such as resiliency and whether you will need any form of scalability in the future, etc.

But to try and answer the question...If you wanted to down the bare minimum path with no redundancy/HA and supply the services above you will need at least 2 servers for Lync. There are some potential additional servers required...

1 Standard Edition Front End (support up to 5000 users, but certainly I'd look at an Ent pool if you were anywhere near that, but not at 30 users) - ideally you would add a second one to pair these for HA
1 Edge Server (for external access)
1 Server for Reverse Proxy (to publish Lync web services)
1 Office WAC (if you intend to share/present PowerPoint presentations)

If your remote users will only ever access via VPN and not via mobile or over the internet directly, you could omit Edge/Reverse proxy.

http://technet.microsoft.com/en-us/library/gg615015.aspx

Had you also looked at Offic

In addition to accessing Lync via VPN, the remote users will probably want to use Lync using their portable devices so we'll need an Edge Server.  If we're not concerned about HA can we run everything on one single Lync Standard Edition Server to act as the Front End, Edge, and Reverse Proxy?

hi - no, you can't. 

front-end, edge and reverse proxy cannot be collocated. You will need a bare minimum of three servers.

the only server you might eventually give up on is the reverse proxy, but you would need to publish the lync web services in an insecure, tricky and unsupported way which definitely you will not want to do only to save 1 VM.

Is the Reverse Proxy server only used to handle Powerpoint presentations?  If we're not interested in using an Office Web App Server for Powerpoint presentations can we do away with the Reverse Proxy server? 

That would leave us with 2 servers: Front End and Edge.

No, the reverse proxy is used to publish Lync web services (which includes ability for Lync autodiscover, mobile connectivity (iPhone/iPad/Windows Mobile/Android/etc) and address book download for Lync clients)

The Office WAC is published via this same reverse proxy though if sharing with external parties is required.

However to fully support external clients you will need both Edge and Reverse proxy.

If you don't mind me asking - is the concern around VM host resources, licensing or

Thank You, so then if I want to integrate mobile devices I'm looking at a minimum of 3 servers?

In addition to the Lync services I mentioned if we want to enable Persistent Chat is this going to require additional servers?

Also, is each server in the topology going to require its own Lync 2013 Standard license?

Sort of.

If you implement just a reverse proxy and no edge, your mobile devices can sign-in but only get IM & presence. (no a/v) and Lync clients won't work externally at all.

If you implement just edge your external Lync clients can sign in but won't get an address book (mobile won't work at all)

Yes persistent chat is another server. [see update below]

No, you only need to license Lync front-end servers. Also there is no difference between standard and enterprise server licenses, they're all the same - it's just an option on install, however SQL is installed as part of standard.

http://office.microsoft.com/en-us/lync/microsoft-lync-licensing-overview-lync-for-multiple-users-FX10378966

Apologies, seems persistent chat has been removed as not being able to be collocated and can be collocated on the front end (I should pay more attention!) and the database can be collocated also.

http://technet.microsoft.com/en-us/library/gg398131.aspx

http://social.technet.microsoft.com/Forums/lync/en-US/517226b7-ae61-46a0-887a-7dbd8d324490/persistent-chat-server-collocation

Sort of.

If you implement just a reverse proxy and no edge, your mobile devices can sign-in but only get IM & presence. (no a/v) and Lync clients won't work externally at all.

If you implement just edge your external Lync clients can sign in but won't get an address book (mobile won't work at all)

Yes persistent chat is another server. [see update below]

No, you only need to license Lync front-end servers. Also there is no difference between standard and enterprise server licenses, they're all the same - it's just an option on install, however SQL is installed as part of standard.

http://office.microsoft.com/en-us/lync/microsoft-lync-licensing-overview-lync-for-multiple-users-FX10378966

Georg has already answered this (no.2 in the thread).

1 standard front end

1 office web apps (if you want to include powerponint sharing, if not, skip it)

1 edge server

1 reverse proxy

total FOUR servers

no need for a persistent chat server, it can be collocated with the standard front-end

No other collocation is possible, so, FOUR is the bare minimum.

hope it's now clear.

Yes thank you, not intersted in Powerpoint presentation sharing so looks like I'll need 3 servers.

I have a couple more questions on having the 3 servers.  If I decide that I want to have 2 front end servers in a pool can they be on Standard or do I have to install Enterprise?

Also, my understanding is that Lync Standard installs SQL Express.  Does Enterprise also install SQL Express or will it require a SQL to run on another box?

Thanks again everyone for their responses.