1-I want to order a call manager business edition with 50 users but extendable to 500 users license in the future.Is this correct?
1 x CUCM6-BE
1 x MCS7828I3-K9-BE
2 x CUCM-BE-10USR
70 x UNITYCN2-ADV-USR
25 x LIC-CM-DL-10=
2-Does the business edition supports SRST?
1. Yes, this looks good :)
I think you only need (as the first 50 mailboxes are covered);
20 x UNITYCN2-ADV-USR
BE contains software and the first 50 seats. Each seat includes a CUCM user and a VM box. These are permanent licenses.
Organizations can select one of the base packages. The Cisco Unified Communications Manager Business Edition base packages bundle the Cisco MCS 7828 appliance with a preloaded software suite and seat licenses for the first 50 users. The seat licenses included in the base package cover the server licenses, mailboxes, and ports needed for the initial system. Note that these seat licenses do not cover phone or device licenses.
2. Yes, BE does support SRST;
Cisco Unified Communications Manager Security Guide for Cisco Unified Communications Manager Business Edition, Release 6.0(1)
Configuring a Secure Survivable Remote Site Telephony (SRST) Reference
Hope this helps!