We migrate to the higher PABX model, which is more reliable and strong in networking (since you have another two premises in the same building, which can be linked to the main node).
Special discount for you only, is around 8-10%.
We need to verify in details for the existing billing system, the operator and the voice mail before giving you the complete solution/price.
In case you want to use Sip mobile device, we have to verify your wireless coverage and data network as well.