Different SIP providers are certified to work with various IP phone system manufactures. Some IP phone system manufactures require additional equipment to operate. Check with an Access Technologies representative to determine if your phone system is certified.
Note: It is important that you test your phone system EXTENSIVELY with the SIP provider before implementing production systems with SIP. Often, demo trunks can be ordered on a monthly basis for this purpose. Test all important features like call forwarding, conferencing, transferring, etc. Often a phone system can be “certified” but certain features can be missing. As an agent, we’ll try to get you in touch with another agent who is using the same type of phone system for technical / feature discussions.