You'll need to have the SIP phone license. It's actually fairly easy. Here are the instructions from the "Feature Description and Operation" manual:
To register a SIP Phone:
1. Select Station User Login (PGM 443) in Device Login section.
2. Enter the desired unused station number as the ID using the format “SIP Phone ID=sip:XXXX”,
where XXXX is the station number. For Example, the SIP ID=sip:1234 is station number 1234.
3. Click the Save button.
SIP Phone
To set-up the SIP Phone:
1. Configure SIP Phone settings (ex. IP address, Subnet mask, Gateway, Telephone number,
Proxy address, Expiration timer, etc.). The Telephone number must be the station number
assigned in Station User Login (PGM 443) and the proxy address is the VOIM8/24 IP address.
2. Boot the SIP Phone, which will register it with iPECS.
Conditions
1. The SIP Phone must be in the same IP domain as the serving VOIM8/24 Module. SIP Phone
cannot support “Direct Send”.
2. The number of SIP Phones is limited by the station capacity of the system. The number of
VOIM channels available limits the number of simultaneous voice/video calls. A SIP Phone
uses a VOIM8/24 channel for a voice call. If two (2) SIP Phones establish a voice call, two
channels are required.
3. A SIP Phone cannot be configured as a Linked Pair station.
4. A SIP Phone can be a member of conference call, but cannot establish a conference call.
5. A SIP Phone can place a voice over call but cannot receive one.
6. The iPECS Station User name is overwritten by SIP Video Phone’s “Display Name” setting.
7. If the Station number is changed in the iPECS database, the SIP Phone should be reconfigured
and re-registered with the system.
8. When SIP Phones are connected in the Point-to-Point mode, the iPECS has no control over the
call. Thus, features such as Camp-on are not supported. In addition, Point-to-Point mode is
not supported for SIP Phones behind a NAPT.
9. Support for SIP phones requires a license key.
Norstar & Vodavi phone systems and network cabling in Gainesville & Ocala Florida