I am experimenting with VOIP with following goal:
Build cost effective and reliable VOIP solution for a company with two branch offices (US and UK) with about 10 staffs each office.
Other general requirement
1. For each sites 4 local PSTN lines are available to connect to the VOIP system
2. Each sites need about 12 extensions (8 VOIP/SIP phone and 4 analog phones as extensions)
3. Provide voice mail functionality for all extensions.
5. Users from either site should be able to dial local numbers from either locations using the PSTN lines
Eg. dialed numbers starting with 9 should dial out through one of 4 PSTN lines connected to US office system
dialed numbers starting with 8 should dial out through one of 4 PSTN lines connected to UK office system
6. Allow to connect to third party VOIP carrier to call any other countries (eg. numbers starting with 7 indicating to use the VOIP carrier to dial out)
Please suggest how can I build solution for this.
Can we use:
1. Cisco SPA9000 as central IP PBX in data center located in US.
2. Cisco SPA400 in each site as PSTN termination - 4 lines; which supports 16 voice mails
2. Cisco SPA8800 in each site as telephony gateway to provide 4 analog extension lines