I found this. I don't think we are allowed to put the link, so I copy/pasted...........
Look at the distances in miles per wire gauge that is being used.
Mitel offers a wide range of products that are used to provide analog connectivity to the PSTN and to analog telephones within the enterprise. Within this range of products are units that have been designed to meet specific market requirements, legacy products that are reaching the end of their life cycle and products designed with the latest technologies.
1. Ensure that the customer is aware that if multiple phones are going to be connected to a single line, then only the model of phone tested successfully should be used, otherwise problems as described above may be encountered.
This document also provides a test procedure that should be used to determine if specific models of ONS phones will work correctly with ONS line cards. This test procedure should be considered in both brand new installations and in existing installations that are undergoing a hardware upgrade. Verifying the operation of ONS phones is extremely important where an existing installation has ONS phones connected to either an SX-2000 PER cabinet or an SX-200 Bay and the PERs or Bays are being replaced with ASU II or AX based ONS line cards.
Parameter
SX2K PER
SX-200 Bay
ASU
AX
ASU II
AMB/AOB
OPS Loss Plan Support
Yes
Yes
No
No
No
No
DNIC Support
Yes
Yes
No
No
No
3300 ICP - No
SX-200 ICP – 2 Ports
LS Trunk Support
Yes
Yes
Yes
Yes
Yes
Yes
LS CLASS Support
No
Yes
No
Yes
Yes
Yes
GS Trunk Support
Yes
Yes
No
No
No
No
REN per line
See Note 1
5
3
3
3 (24 port)
2 (16 port)
2 (4+12 Port Combo)
3 (24 port)
2 (16 port)
2 (4+12 Port Combo)
2
Open Circuit Ringing Voltage
(VRMS)
Dependant on power supply country variant, see Table below.
Nominal = 90
Maximum = 100
Minimum = 70
Nominal = 65
Maximum = 72
Minimum = 58
Nominal = 55
Maximum = 55.5
Minimum = 54.5
For China Nominal voltage = 62
Nominal = 55
Maximum = 55.5
Minimum = 54.5
For China Nominal voltage = 62
Nominal = 55
Maximum = 55.5
Minimum = 54.5
For China Nominal voltage = 62
ONS Loop Length (Miles)
2.3 (22 AWG) NA
1.4 (24 AWG) NA
0.9 (26 AWG) NA
2.3 (22 AWG)
1.4 (24 AWG)
0.9 (26 AWG)
2.3 (22 AWG)
1.4 (24 AWG)
0.9 (26 AWG)
5.17 (22 AWG)
3.25 (24 AWG)
2 (26 AWG)
300 ohm set
5.17 (22 AWG)
3.25 (24 AWG)
2 (26 AWG)
300 ohm set
5.17 (22 AWG)
3.25 (24 AWG)
2 (26 AWG)
300 ohm set
ONS Long for Germany
Yes
N/A
No
No
No
No
ONS Line Feed Voltage
See Note 2
27 V
27 V
27V
48 V
(24 V short loop)
48 V
(24 V short loop)
48 V
(24 V short loop)
ONS WMI Lamp Strike Voltage
(VDC)
See Note 3
Nominal = 115
Minimum = 110
Nominal = 175
Minimum = 150
Nominal = 115
Minimum = 110
Nominal = 108
Minimum = 105
Nominal = 108
Minimum = 105
Nominal = 108
Minimum = 105
ONS On Hook Detection Current
<12 mA
<12 mA
<3.5 mA
<3.5 mA
<3.5 mA
<3.5 mA
OPS Loop Length (Miles)
3.6 (26AWG)
9.4 (22 AWG)
3.6 (26AWG)
9.4 (22 AWG)
N/A
N/A
N/A
N/A
OPS Line Feed Voltage
48 V
48 V
N/A
Future Capability
Future Capability
Future Capability
IP Networkable
No
No
No
Yes
No
N/A
Power Supply Redundancy
No
No
No
Yes
No
No
48 VDC Support main supply
Yes
No
No
No
No
No
Number of ports
192
96
24
288 Standalone
48
AMB = 10 AOB = 10
Number of TDM Channels to chassis
128
96 on SX-200
64 on ICP
32
128–IP Channels
48
20
Connectivity to ICP
FIM
FIM/CIM
CIM
IP
CIM
N/A
Country/Regions Supported
CH, DE, HK, IT, MA, NA, NZ, TA, UK
See Note 4.
NA
AU, BR, CH, DE, ES, FR, IT, LA, NA,NL,NZ, PT, UK
AU, BR, CH, DE, ES, FR, IT, LA, NL, NA, NZ, PT, UK
AU, BR, CH, DE, ES, FR, IT, LA, NL, NA, NZ, PT, UK
AU, BR, CH, FR, DE, ES, IT, LA, NL, NA, NZ, PT, UK
Note 1: These values are the REN per individual line. Contact Professional Services to determine how many phones the system can ring simultaneously.
Note 2: The ONS Line Feed Voltage will switch from 48 V to 24 V automatically based on loop current, the different voltages cannot be selected manually.
Note 4: HK, MA and TA are currently not supported on the 3300; ASU, ASU II, AX or AMB/AOB.
N/A = Not Applicable
Table 1 Analog Interface Comparison
Power Supply Variant
MP914AA
North America
UK (Obsolete)
MP914AD
UK (EN60950 Approved)
MP914AC/E
Germany
Frequency, Hz
20
25
25
Nominal, Vrms
80
80
75
65
Maximum, Vrms
83
81
80
68
Minimum, Vrms
77
74
72
58
Table 2 SX-2000 Open Circuit Ringing Voltage
Background
The Ringer Equivalence Number or REN, is unit of measurement that is used by Mitel to specify how much loading a particular analog phone set will present to the ringer circuit on a line card. A REN of ‘1’ represents the ringer loading effect of one ‘2500-type’ phone set. 2500 type phone set refers to a Western Electric Model 2500 or equivalent, these telephones have a 12 button DTMF dial pad and a most importantly an electro-mechanical ringer. The REN values of modern analog phones where the ringer is powered from the phone line will typically have a REN value between 0.6 and 0.8, while an analog phone that has its ringer powered from an external AC adapter could have a REN value as low as 0.1. Analog phones should have their REN value indicated on the base of the phone or in the phone’s documentation.
If a line card supports a REN of 3 per line, then only three ‘500’ type sets can be connected to an individual line on this line card because the three sets will add up to a REN of 3. Connecting a fourth ‘500’ type set to the line will exceed the line circuit’s capabilities and the line card may not be able to successfully ring the phones causing ‘ring trip’. Ring trip is a situation where the PBX acts as if the phone has entered an off hook state even though the phone is still on hook.
Exceeding the REN capabilities of a line circuit can also cause problems with the visual Message Waiting Indicator (MWI). Further compounding problems with MWI lamps is the fact that there is not a definitive industry standard governing what the strike voltage value should be for analog phones and the fact that the strike voltage for neon MWI lamps will potentially change over long periods of time due to aging of the neon lamp.
As can be seen in Table 1; the various line cards offered by Mitel support different values of REN. For instance an SX-2000 PER ONS line card supports 5 REN per line, but the 3300 AMB/AOB supports only 2 REN line.
Because of the different REN per line specifications on Mitel’s various line cards it is important that samples of a customer’s analog phones be tested with the line card that the Sales Engineer or Dealer intends to sell to this particular customer. To ensure correct operation of analog phones with a given line card the following test procedure must be followed, the testing can be performed either at the customer site or in the Regional Sales office.
Test Procedure
2. Using table 1, determine the REN per line specification of the line card intended for this particular installation.
3. To increase the sample size, obtain as a minimum at least two of these line cards.
4. Obtain a quantity of the analog phones intended for this application.
5. Use the REN per line rating of the line card to determine how many phones should be connected to a single line circuit. For instance, if the line card has a REN per line value of 3, then connect three phones to one of the line card’s line circuits. Three more phones should be connected to the line card’s second circuit and so on to increase the sample size.
6. More phones should be connected to the second line card in the same way described in step #4 so that more than one line card is tested.
7. Call the phones on the circuit under test.
8. Ensure that all phones on the circuit ring correctly.
9. Leave a voice mail message on each of the circuits under test.
10. Ensure that all of the MWI lamps on the circuit under test illuminate.
11. Call the phones on the circuit under test again.
12. Ensure that all of the phones on the circuit under test ring and ensure that all of the MWI lamps flash during the ring cycle.
13. If these telephones do not pass the above tests then these telephones CANNOT BE USED for this sale or installation and suitable phones that are able to pass the tests will have to be purchased.
14. If these telephones pass the above tests then you can proceed with the sale or installation.
15. Regardless of whether the phones pass or fail the above tests the test results should be recoded and filed by the Sales Engineer in the Customer’s file.
Because of the wide variety of products offered by Mitel, it is important that the Pre-Sales Engineer and the customer be aware of the differences in functionality and capabilities between the various products. For instance, when a customer that is using legacy products such as the SX2K Peripheral Shelf or the SX-200 Bay is considering replacing the legacy product with a current offering it is very important to identify up front if there will be any network redesign required prior to installing the newer product. Table 1 can be used to identify key differences between analog connectivity products offered by Mitel. Table 2 provides the SX-2000 open ringing voltage values for various line cards.
