Panasonic KX-TDA0480 Getting Started page 47

A3 Optimising Performance
When implementing a VoIP network, care must be taken when assessing bandwidth
requirements. The VoIP Gateway Card uses 12 kbps per call when in use by default.
Serialisation delays to the WAN are lower when higher bandwidths are used.
When using the Internet/VPN, the ISP plays an important role in reducing the variable delay in
the WAN. A regional or national ISP will usually have better connectivity with the backbone and
will be able to guarantee greater service reliability than a local city ISP. When using VPN
facilities, delays may be introduced due to the additional processing time required for
encryption processing.
Getting Started 47