If have not, for small 3 person office you need 1760-V voice-enabled router (software included) with VIC-4FXS/DID and WIC-1T (for WAN) modules in EACH office. You can use common analog phones.
You want to connect offices through the Internet? Its not good solution, because of voice quality may be bad. Ask your provider about Frame Relay (for example) channels.
If you plan to increase quantity of employees at office you can simple buy CCME (CallManager Express)license for router, buy Cisco IP Phones, Catalyst switch (2950 for example) and setup IP Telephony in your office, up to 24 phones.
IntroductionCUCM Routing RulesDial String implementation PolicyCUCM Routing LogicSIP URI Call Routing Analysis+++ Case Study: 1 ++++++ Case Study: 2 +++Conclusion
Over the last few months, I have had the privilege of working on SI...
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...