Switching

Equipment

There will be one XY exchange and then the regular 1DSS Exchange. To save on equipment, the first selector will be digit-absorbing on the XY if the first digit on that exchange is dialed, meaning that the levels 1, 2, and 3, and 0 on each exchange cannot be used, and 9 will also be a reserved level (i.e. ringback via 958, and echo test, loop around, silent termination, milliwatt, on other 9xx numbers), allowing for a maximum 5,000 numbers per exchange or 10,000 numbers between the two. You may make a call on your exchange by simply dialing the last 5 digits of the telephone number. To call an exchange elsewhere in Montana you must dial 1+Number (even if it is an exchange just a few miles away; don't worry since it is in your LATA You will not be charged).

To dial a long-distance call, you must dial 1 + the area code + the number. The charge will appear on your bill. If you make a high volume of long-distance calls you may opt for our "flat-rate" long-distance package which is an additional $20/month and allows unlimited long-distance calls within the United States. International telephone calls must be placed through the long distance operator or by dialling 011 + CC + Number. Complimentary access is provided to the VoIP switching networks C*NET (Collectors' Network) and NPSTN. Competitive long-distance carriers can be accessed using Feature Groups B and D. 10-10-xxx codes are available by dialing 10-xxx (10-10-xxx codes used to be 10-xxx before we ran out). You may also use Feature Group B codes by dialing 950-xxxx. See Feature Groups for more info on competitive long-distance. You are responsible for ensuring you do not get scammed — we highly recommend the use of regular 1+ long distance which will complete over our high quality long distance circuits to the 1DSS Switch and then out to the rest of the phone network.

The toll switch (and Inter-Office switch) will be the #1DSS (No. 1 Digital Switching System) switch, which is currently in development. The No. 1 DSS is a soft-switch that will sit between the rest of the PSTN and the phone equipment located in Oakwood.

Special codes, such as 0 and 11x/11xx/10xxx will function normally. You may dial vertical service codes as 11xx (via 1DSS). You must dial 113 for information instead of 411; likewise, you must dial 114 for repair, not 611, and you may dial 112 for the long distance operator. If you are on a party line, you can ring other parties on your line by dialing 118x, and you can get the time by dialing 119. In an emergency, dial 0 and tell the operator there is an emergency; tell the operator your address and telephone number and she will relay it to an available dispatcher. All operators are trained to handle emergencies and the operator switchboards are always staffed, both at cordboards (dial 0) and TSPS positions (112 long distance operator). You may also dial 911 and you will be connected immediately to the county's 9-1-1 System; your address, name, and other useful information will automatically appear on the 911 Operator's screen so he or she can better assist you in an emergency. Emergency operator assistance accessed by dialing 0 is local; assistance accessed by dialing 911 is regional.

Each house will have two copper pairs run to it — one connected to an electromechanical switch and used for voice calls and one connected directly to the No. 1 DSS. This second line is specifically designed for use with modems, alarms, LifeLine, pacemakers, etc. so that inter-computer communication does not impede the ability to make and receive telephone calls. Since each house will come equipped with two 4-wire pairs (a 4-pair drop), this means that with the basic wiring configuration installed when a house is built, the ability to have 2 voice lines and 2 modem lines already exists. Further lines will require additional drops by the telephone company. By default, only 1 line is provisioned on each pair. While local calls on both pairs are free, the data pair is only designed for use with modems or special equipment requiring it and is not intended for use with telephone sets. The long-distance plan that applies to the data pair is the same plan that applies to the voice pair.

The charge for the data pair will be $1 per month for residents who already have an analog pair for voice (i.e. it functions as a bundled services). A phone number is assigned to each data line so that modems can be called back (i.e. modems can receive incoming calls) from other modems in Oakwood and the "outside world".

The Mountain Pacific Telephone Company has already been formulated. It will eventually serve as Oakwood's primary incumbent telephone provider.

Double Header Trunks

The idiotic and moronic Kari's Law and Ray Baum Acts (not to mention 988) serve to do little more than screw up the elegance of the telephone network and made it a hodgepodge of patchwork dialing patterns. At this time, we do not expect that PBXs in Oakwood will adhere to Kari's Law.

However, one approach that would allow lines serving PBXs to be compliant (if only to say that they are compliant), would be to use double header trunks. This same technique was used on SxS systems to provide simultaneous access to the long-distance network by dialing 1+ as well as local 11X codes, such as 113 for information (before 411). The solution is simple but elegant, and operates as follows:

Other areas retained 1-1-3 by installing what was known as "double-header" trunks, which actually connected the call to the long distance equipment and then "snatched it back" if the second digit was also a "1". — The relationship between 411, 113, and long-distance-dialing (Wikipedia)

This kind of trunk is - for better or worse - known by many names. In fact, we are not even sure what the correct name really is. Here are other names by which this kind of SxS switching component might be known:

• Double Header Selector
• Double headed trunk — In the conventional step-by-step dial switching telephone systems employing 11X service codes for service code calls and the single digit l for access to the toll dialing network, the first digit dialed is used to step the first selector to the level dialed (level one) allowing'this selector to seize an auxiliary trunk double headed which in turn seizes both an outgoing trunk and a service code selector. — Google Patents
• "Wannan (Service Code) Selector" — used by Bell Canada to provide access 1 calls to DDD instead of the earlier 112 for DDD access.
• Sub-office selector-repeater (WECo)/Switching selector repeater (AE) — used when a level is shared between a small sub-office and the larger main office on which it is homed.

Effectively, this kind of selector puts through two calls at once. Once more digits are dialed and the switchtrain has more information, the "extra" (wrong) call is dropped. This is different from using a timeout as is done on today's electronic switches, because there is no delay whatsoever with this kind of selector. There are no timeouts — two calls are literally being dialed at once, and rather than completing the call when we have more information, two calls are initiated at once and the wrong call is dropped when further information is obtained. This minimizes the inconvenience to the subscriber and results in a more seamless experience.

So, how would this help?

Rather than "double up" on 1+ and 1-1-X, we would double on 1+ and 1-1, as well as potentially 1-1-X for 11X codes and possibly 1-1-X-X for some vertical service codes. Rather than expect subscriber equipment to do anything different, we would essentially "short-circuit" the "11" code on PBX lines to the regional 911 PSAP. This would be done only on lines provisioned for PBXs so as to minimize the amount of false calls or misdials to 911.

In this manner, a PBX subscriber will dial 9 for a central office line as usual. However, if he were to inadvertently dial 9-1-1 (that is 9, followed by 11), rather than 9-9-1-1 (9, followed by 911), he would still be connected with the PSAP. Thus, the code 11 will go to the PSAP (in addition to 911 as usual).

This could be easily and unobtrusively accomplished using the aforementioned double header trunk. On a PBX line, upon dialing 1, the call would end up in one of these special selectors. Immediately, the call will be split into 2, with one trunk for CAMA/long-distance and one trunk for 11+ (as in 11, 11X, or 11XX). There are 3 possibilities now.

First, if a 0 is dialed, the call will continue through the switchtrain to Feature Group D trunks (since 10 has been dialed). Both the long-distance and 11+ trunks will be dropped.

If a 2 through 9 has been dialed, the call will continue to the long-distance equipment, since 1 has been succeeded by the start of a numbering plan area code. The 11+ trunk will be dropped.

Lastly, if a 1 is dialed, since a "11" will have been dialed, a call will be immediately initiated to the PSAP as well as to 11X selector. The long-distance trunk will be dropped. However, if a caller dials another digit, the first call to the PSAP will be immediately dropped and the call will continue through the switchtrain for 11X/11XX. A similar procedure can then be used to distinguish between 11X and 11XX calls — if yet another digit is dialed, the 11X call will be dropped and the 11XX call will remain connected. In other words, at each selector, the switchtrain is split into two paths and the "wrong" one is dropped if/when another digit is dialed.

This solution is optimal, as no equipment modifications outside of the central office are necessary, there is no delay on completing either correctly dialed (9+9-1-1) or incorrectly dialed (9+1-1) PSAP calls, and there is no inconvenience to subscribers attempting to dial 1+, 11X, or 11XX calls. PSAP and 11X operators would be aware of the potential for dropped calls and would be able to recognize an abrupt disconnect as the result of dialing further digits. In most cases, we would expect customers intending to reach 11X/11XX to dial the additional digits required to complete those calls to do so before the 911/11X operators would answer.

Brief Summary: Dialing "1" from a PBX line will connect to the first double header selector. If anything but a 1 is dialed, the 11+ trunk will be dropped. If a 1 is dialed, the long-distance trunk will be dropped. At this point, the PSAP operator will be immediately rung. If an additional digit is dialed, the PSAP call will be dropped and the appropriate 11X operator will be immediately rung. If an additional digit is dialed, the 11X operator will be dropped and the appropriate 11XX VSC will have been dialed.

TouchTone Dialing

Only rotary telephones will work for dialing unless you have LifeLine or some special service. If you want to keep using the main line but want to use TouchTone phones, please contact the Business Office so we can fit your line with a TouchTone to "Pulse" Converter. Regardless, customer-owned TouchTone telephones may be used to navigate IVR menus. There will be no additional charge for extra telephones on your line. Some states, such as Minnesota, do not allow charging for tone dialing. It will need to be researched as to whether Montana has any stance on this policy.

Certain line groups will be dedicated to subscribers who subscribe to TouchTone service (since TouchTone converters are installed on a per-line group not per-line basis). Aftermarket (e.g. Teltone) TouchTone converters are strapped to the back of the framework and are wired in the T&R between the linefinders and first selectors. A 200 line linegroup would require 20 converters. The WECo scheme for adding TouchTone is more complex and more rare at this point. Some options on the linefinders include Normal Post Springs that are programmable with little bendable tabs, so that special features/functions are available on certain L&CO groups. One way of rigging things would be to put Touch-Tone service only on certain L&CO groups. Possibly, this means dial-only customers who want to upgrade to TouchTone service would need to get a new number.

In SxS and XY C.O.s, each line (tip,ring, sleeve) are brought out to the horizontal side of the frame, along with each connector terminal (tip, ring, sleeve) and are strapped together there. From that point, tip and ring are then cross-connected to cable pairs. This is how you can have multiple connector numbers on the same line. With that type of deployment, you could move somebody's connector number to a line in a different line group. Doing it as described above does make for a cleaner distribution frame for sure.

An alternative to converters at the C.O. is also possible individual converters installed in a subscriber's NID (on customer's premises). If a custom solution is developed, it will almost certainly have to meet, among other things, FCC regulations.

Summary

Touchtone may be offered on the ElectroMechanical switch. It has not yet been determined if a charge will be assessed for Touch Tone service (Montana Public Service Commission (PSC) may or may not permit a charge for touchtone service) Once the ElectroMechanical switch is up and running, real-world testing will need to be done to see how TouchTone decoders behave on equipped line groups to see if anything can be done to make a 1+7-digit call complete faster (other than dialing 1+10-digits).

Dial plan

Local calls on this switch will be 7 digits — (Number)
Calls outside this switch to local 406 numbers with be 8 digits (1+Number) — the unfortunate side affect of this is that a delay will be needed after the 8th digit to determine if they are dialing 8 or 11 digits. The position could be taken that if someone doesn't like the delay following 1+7D dialing, 1+10D will eliminate the delay, e.g. dialing 1-406-318-8463 will connect faster than 1-318-8463 would.
Calls outside 406 area code (1+Area Code+Number)
Calls to international numbers (011+Country Code+Number)

According to NANPA these are the only available (NNX) Office codes in the 406 NPA:
997 (WYandotte, WYman, WYndown)
990 (WYandotte, WYman, WYndown)
985 (YUkon)
955 (Cannot be used, No Telephone Exchange name)
341 (DIamond, DIckens, FIeldbrook, FIeldstone, FIllmore, FIrestone)

So our Central Office will be FIeldbrook1-XXXX (341-XXXX).

We will also reserve 997 and 990 for future use so we will have:
FIeldbrook 1-XXXX (XY Switch)
WYman 0-XXXX (Future Use)
WYman 7-XXXX (Future Use)

So here is the dial plan once more:
Local Calls: FIeldbrook 1-XXXX, WYman 0-XXXX, WYman 7-XXXX (normal)
Calls outside of Oakwood: 1+Number (was common in the 50s, 60s, 70s, etc...)
Calls outside of Montana: 1+Area Code+Number (Normal)
International Calls: 011+Number (Normal) or 0 (operator assistance required)

This is getting the most out of the XY switch we already have.

Summary

Calls originating from lines served by a digital C.O. dialing 1+7-digits will notice a short delay (maybe 5 seconds) before their call is completed, but may hit # to make the call complete faster. Calls originating from lines served by an electromechanical C.O. dialing 1+7-digits will notice a short delay (maybe 5 seconds) before their call is completed.