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.

www.northfloridacommunications.com
Norstar & Vodavi phone systems and network cabling in Gainesville & Ocala Florida

Thanks nfcphoneman...
This is very good! Thanks.
I gave a star to you.

MAYBE you could also make a step-by-step list of how-to-install a SIP trunk in the IPECS 5.0?

///doktor

Or maybe you could comment on this thread concerning how-to-install a SIP trunk in IPECS...   thread1613-1545008: ipecs 5.0 and sip trunk: ipecs 5.0 and sip trunk  

///doktor

Hello
Can i use test licens ?

abl2910
 

Sure, you can use the test license.

www.northfloridacommunications.com
Norstar & Vodavi phone systems and network cabling in Gainesville & Ocala Florida

Thanks for the star, Doktor.  However, it didn't take much effort to cut and paste. ;)

www.northfloridacommunications.com
Norstar & Vodavi phone systems and network cabling in Gainesville & Ocala Florida

OK.
I suggest that my plan for implementing the SIP trunk in IPECS is working well?

///doktor

Hello nfcphoneman

I have done the profil i prg 443 and can't call anyone
Then i make a profile in prg 126 on all the ext.
ex. 100, 101 and 102(102=sipphone), then i could dial from sip to ipphone 100 and 101 and speak, but from ipphone to sipphone i can't.I can't dial outgoing line.
the sipphone is not registratet in prg 102

Your first tread was a good help.

Abl2910

Hello
The speak is one way from ip to sip

abl2910

Do you have any firewall that can affect this?
Try to disable the firewall for testing purpose...

///doktor

Hello doktor
No firewall it's on same lan

abl2910
 

I have not really played with it a lot, altough I did get a couple of devices working.

I suggest you download a copy of X-Lite (free softphone) and try to connect with it.  If that works, then you have some settings to play with on your SIP phone.

www.northfloridacommunications.com
Norstar & Vodavi phone systems and network cabling in Gainesville & Ocala Florida

Hi abl2910 and nfcphoneman

I would like to be able to post a "white paper" (Gold Corn Document) on how you managed to get a SIP phone to work with IPECS here in this forum...
Like this:

Initiate so and by programming - PGM xxx BTN yyy with the follwong data. Just easy and in step-by-step.

Can you do this?

Like the "How to install an IP phone (or IP trunk) in ipLDK" like I wrote one of the threads.
 

///doktor

Hello
I have try x-lite it's working from sip to ip with 2 way speak.But i can't call from ip phone to sip, sip number not valid is the fault.
I have update firmware in the lip 6830 and now 2 way speak, but still no ip to sip call
In prg 443 it's looks like it is not connected.
Just for info

For the step by step guide, it's not ready for that now.
I have no outgoing line from sip phone and no ingoing call to sip.

abl2910

OK, abl2910...
We will wait for your good update.

///doktor

Hi All

I have received a step-by-step installation guide on  "How to install an IP phone (or IP trunk) in iPECS".

Let me know if you need it...

Please use this link to see my address...
http://www.kandu.dk/spg97163.aspx  

///doktor

Hello
Thanks for the guide, but i cant registrate a sip phone
I program the user login in prg443 but don't get the phone registrate in prg102

I can make the ip-phones data as sip in prg126 then i can call from the sip phone to the ip phone but not from ip-phone to sip-phone, fault device not valid

maybe i need licens

Is there anyone that have connected a sip phone(lip6812) to ipecs v5 with luck two way speak out going lines etc.
then i am interested to hear from them.

abl2910

Hello

The use of sip extention, you need
like nfcphoneman says programming in prg 443 user login and prg 133 set it to inbound and a licens for every used sipphone
test licens work

abl2910

I realize this thread is old, but while programming a new system, I ran into the same problem that abl2910 was describing.  I could call from a SIP phone to an iPECS phone, but could not call from an iPECS phone to a SIP phone.  After a few hours, I discovered that "use outbound proxy" in SIP G/W Attributes (133) has to be off in order for the SIP phone to connect.  Fortunately, this did not interfere with my SIP trunking.

www.jacksonvilletelephone.com
Jacksonville Florida Telephone Systems