We are a school corporation in northern Indiana and have recently replaced our Hicom 300 PBX with a Cisco Call Manager based IP PBX. Currently we use multiple T1-PRI circuits to provide local loop services to our schools.
Because we receive funds from the E-Rate USF funding programs, each time our local service contract comes up for renewal we must entertain proposals from various companies for our local loop circuits and then select the most economic proposal that meets our needs . Our recently published RFP asking for proposals to replace our exiting T1-PRI circuits opened the possibility for vendors to offer alternatives to T1-PRI technology for delivery of the local loop.
Needless to say we had quite a few vendors provide proposals that utilize alternatives to T1-PRI local loops. Both of the two alternatives used IP based technology to deliver local loop. The first was T1-PRI over IP. The other was SIP trunks.
However, during our discussions with many of the various vendors a repeated underlying issue was T.30 fax delivery as well as modem signal delivery. Many of the vendors expressed concern that our numerous fax machines and modems could not be reliably transported using SIP technology. A few of the vendors even expressed concerns about T1-PRI over IP. Other just blew off the issue with statements like, “We have never had any issues with faxes delivery, and it should be no problem”. (Those guys make me wary)!
Some vendors offered external fax "mailboxes" which then got sent to our internal email systems. (Of course that does not address outbound fax delivery).
After looking a little closer and some research I have determined (and please correct me if I am incorrect in my assessments) that the reason SIP trunking has issues with T.30 service (and modem delivery) has to do with timing issues related to IP based packet delivery. From what I understand SIP has particular difficulty with T.30. Further, as I understand, the T.38 protocols have been developed to address these timing issues with SIP trunks.
None of the vendors offered T.38 systems, thought I understand our Call Manager 7.x systems is T.38 ready (or at least I am told it is).
My question is multipart:
1) If T1-PRI over IP is delivered via IP technologies, it is not also prone to these same timing issues?
2) Have any of you come up against these T.30/Modem issues with the SIP trunking, if so how did you deal with it?
3) Have any of you ever used T1-PRI delivery over IP and if so, what issues to I need to be vigilant with.
4) IS a Cisco Call Managers IP Phone system T.38 ready or does other hardware / software have to be provided on our end
Network Administrator - Communications & Security Services
Merrillville Commuity School Corp.
276 East 68th Place
Merrillville, IN 46910
Because we receive funds from the E-Rate USF funding programs, each time our local service contract comes up for renewal we must entertain proposals from various companies for our local loop circuits and then select the most economic proposal that meets our needs . Our recently published RFP asking for proposals to replace our exiting T1-PRI circuits opened the possibility for vendors to offer alternatives to T1-PRI technology for delivery of the local loop.
Needless to say we had quite a few vendors provide proposals that utilize alternatives to T1-PRI local loops. Both of the two alternatives used IP based technology to deliver local loop. The first was T1-PRI over IP. The other was SIP trunks.
However, during our discussions with many of the various vendors a repeated underlying issue was T.30 fax delivery as well as modem signal delivery. Many of the vendors expressed concern that our numerous fax machines and modems could not be reliably transported using SIP technology. A few of the vendors even expressed concerns about T1-PRI over IP. Other just blew off the issue with statements like, “We have never had any issues with faxes delivery, and it should be no problem”. (Those guys make me wary)!
Some vendors offered external fax "mailboxes" which then got sent to our internal email systems. (Of course that does not address outbound fax delivery).
After looking a little closer and some research I have determined (and please correct me if I am incorrect in my assessments) that the reason SIP trunking has issues with T.30 service (and modem delivery) has to do with timing issues related to IP based packet delivery. From what I understand SIP has particular difficulty with T.30. Further, as I understand, the T.38 protocols have been developed to address these timing issues with SIP trunks.
None of the vendors offered T.38 systems, thought I understand our Call Manager 7.x systems is T.38 ready (or at least I am told it is).
My question is multipart:
1) If T1-PRI over IP is delivered via IP technologies, it is not also prone to these same timing issues?
2) Have any of you come up against these T.30/Modem issues with the SIP trunking, if so how did you deal with it?
3) Have any of you ever used T1-PRI delivery over IP and if so, what issues to I need to be vigilant with.
4) IS a Cisco Call Managers IP Phone system T.38 ready or does other hardware / software have to be provided on our end
Network Administrator - Communications & Security Services
Merrillville Commuity School Corp.
276 East 68th Place
Merrillville, IN 46910