OPINION
WINFREE, Justice.
I. INTRODUCTION
A local telephone company proposed moving its first point of switching for routing telephone traffic. Two long-distance carriers affected by the proposal opposed the change, and an association of local telephone companies sought to intervene in the ensuing regulatory proceeding. The agency denied intervention, the superior court affirmed, and the association appeals. We affirm denial of intervention because the agency reasonably concluded that the association did not qualify for mandatory intervention and did not abuse its discretion in denying permissive intervention.
II. FACTS AND PROCEEDINGS
Long-distance telephone companies (inter-exchange carriers, or IXCs) need the facilities of local telephone companies (local exchange companies, or LECs) to originate and terminate intrastate toll calls. Prior to 1989 long-distance carriers compensated local telephone companies for use of their facilities through a settlements process. In 1989 the Alaska Public Utilities Commission, predecessor to the Regulatory Commission of Alaska (collectively, Commission), created the Alaska Exchange Carriers Association, Inc. (AECA), an association of local telephone companies Creation of AECA represented a shift from the settlements process to one involving tariffed access charges.
Under the old settlements process, each long-distance telephone company negotiated with each local carrier individually. Under the new system, AECA calculates a single access charge tariff for all of its members. The tariff:
[RJefers to the contract of the 21 members of AECA wherein they agree to share facilities and services with intrastate long-distance companies, related to long-distance calls originating from or coming into Alaska. The tariff also lays out a system of access charges that the local carriers charge the long-distance carriers for use of their networks.
In October 2006 AECA member Interior Telephone Company, Inc. petitioned for authorization to move its first point of switching, following procedures outlined in AECAs tariff, The first point of switching is:
The first exchange carrier location at which switching occurs on the terminating path of a call proceeding from the IXC terminal location to the terminating end office, or the last exchange carrier location at which switching occurs on the originating path of a call proceeding from the originating end office to the IXC terminal location.[]
Put another way, a switch is a device that routes telephone traffic, and the first point of switching, or FPOS, is the physical point where a local AECA member company interconnects with an interstate long-distance service provider. According to Interior Telephone, moving the FPOS would benefit consumers by making additional services available in a cost-efficient manner. Two long-distance telephone companies, GCI Communication Corp. d/b/a General Communication, Inc. and Alascom, Inc. d/b/a AT & T Alascom, opposed Interior Telephones proposed FPOS change partly because they believed it would impermissibly shift some costs to them.
The Commission designated GCI and AT & T as parties to the regulatory proceeding without requiring petitions to intervene, noting that AECAs tariff anticipates that objecting access customers will participate in a proceeding before the commission. The Commission further stated: We require any interested person wishing to file a petition to intervene in this proceeding to file that petition by October 20, 2006. Our criteria for evaluating petitions to intervene are set out at 3 AAC 48.110.
AECA timely filed a petition to intervene, arguing that under 3 AAC 48.110 it had a statutory right to intervene or it qualified for permissive intervention. Interior Telephone supported the petition; GCI and AT & T each filed an opposition.
On November 80 the Commission denied AECAs petition to intervene, likening the case to Docket U-99-81, in which the Commission had previously decided AECA neither had a statutory right to intervene nor qualified for permissive intervention. On December 12 AECA filed a petition for reconsideration and moved for expedited consideration. On December 20 Interior Telephone filed a memorandum - supporting AECAs petition; that same day, GCI and AT & T each filed an opposition.
On December 28 the Commission granted AECAs motion for expedited consideration but denied its petition for reconsideration. The Commission reiterated that AECA had no statutory right to intervene and that permissive intervention was not warranted. AECA appealed to the superior court, and Superior Court Judge Sen K. Tan affirmed denial of AECAs intervention motion in April 2007.
In June 2007 the Commission held a public hearing on Interior Telephones petition to change the FPOS. The Commission denied the petition in October.
AECA appeals the denial of intervention.
III. STANDARD OF REVIEW
When a superior court acts as an intermediate court of appeals, we independently review the administrative decision. Where questions of law do not involve agency expertise, the appropriate standard of review is substitution of judgment; where agency expertise is implicated, the rational basis standard applies. Under the substitution of judgment standard, we make our own legal interpretations. Under the rational basis standard, we defer to agency interpretation if it is supported by the facts and has a reasonable basis in law. We review an agencys application of its own regulations for whether the agencys decision was arbitrary, unreasonable, or an abuse of discretion. Findings of fact are reviewed for clear error under the substantial evidence standard. Findings are upheld if they are supported by relevant evidence that a reasonable person might accept as adequate to support them.
Here, the proper standards of review are (1) rational basis for whether AECA qualifies for intervention as a matter of right under 3 AAC 48.110, because the Commission is in a superior position to interpret its own regulation, and (2) abuse of discretion for whether AECA qualifies for permissive intervention under 3 AAC 48.110, because the Commission is applying its own regulation to the facts of the case.
IV. DISCUSSION
A. Arguments and Rulings Below
AFCA first argues that it has a statutory right to intervene under 3 AAC 48.110(a), which provides: Any person who has a statutory right to be made a party ... will be permitted to intervene. AECA concedes that there is no express provision of the Utilities Act stating that a utility or its ratepayers may be heard with regard to issues arising under a tariff But according to AECA, the basic tenet, that a party may be heard with regard to disputes arising under its own tariff, is implied in virtually every tariff-related provision of the Utilities Act. AECA argues that the issues in this case affect AECA as a whole, as well as AECAs tariff, AECAs billing and collection of access charges, AECAs distribution of access charge revenues, and AECAs twenty other member companies.
AECA also argues that it qualifies for permissive intervention under another portion of 3 AAC 48.110(a), which provides: Any person whose intervention will be conducive to the ends of justice and will not unduly delay the conduct of the proceeding will, in the commissions discretion, be permitted to intervene. 3 AAC 48.110(b) specifies seven permissive intervention factors:
In passing upon a petition to intervene, the following factors, among others, will be considered:
(1) the nature of the petitioners right under statute to be made a party to the proceeding;
(2) the nature and extent of the property, financial, or other interest of the petitioner;
(8) the effect on petitioners interest of the order which may be entered in the proceeding;
(4) the availability of other means by which the petitioners interest may be protected;
(5) the extent to which petitioners interest will be represented by existing parties;
(6) the extent to which petitioners participation may reasonably be expected to assist in the development of a sound record, including the issues that petitioner intends to address in the proceeding; and
(7) the extent to which participation of the petitioner will broaden the issue or delay the proceeding.
The Commission found the facts and circumstances of this case substantially identical to those in Docket U-99-81 and, for the same reasons as in that case, denied AECAs petition. The local telephone company in Docket U-99-81 had moved its first point of switching from North Pole to Fairbanks. The tariff then in effect required local and long-distance carriers to agree to change the first point of switching, but the carriers had not reached an agreement. AECA attempted to intervene, arguing-as it does in this case-that it had a statutory right to intervene in any proceeding in which the interpretation and application of its tariff is at issue. The Commission rejected that argument. The Commission considered the permissive intervention factors of 3 AAC 48.110(b), but denied AECAs motion to intervene, noting that: (1) neither AECAs property nor financial interests were affected; (2) although AECAs input could arguably assist the Commission, proper interpretation of the tariff was within the Commissions purview; (8) AECAs participation could not reasonably assist in developing a sound record because the local and long-distance carriers already had presented both sides of the issue; and (4) AECAs participation could actually delay proceedings.
The Commission also noted that AECA failled] to acknowledge [the order in Docket U-99-81] in its petition. In denying AECAs subsequent motion for reconsideration, the Commission stated that AECA had no statutory right to intervene and that intervention based on the discretionary intervention factors was not warranted.
The superior court affirmed the Commissions decision, first reiterating that no express statutory right of intervention existed. The court reasoned that whether the term statutory in 3 AAC 48.110(a) encompassed implied statutory rights was a matter of the Commissions interpretation of its own regulations, and thus subject to the reasonable basis standard of review. The court concluded that [blased on the language of the regulation, a reasonable basis existed for the Commission to deny AECA intervention.
The court then stated that while some permissive intervention factors weighed in favor of allowing intervention, others weighed against it, and it concluded the Commission had not abused its discretion in denying AECAs motion for permissive intervention. The court noted that the only seetion of the tariff at issue was § 2.6, which deals only with obligations of the parties before a petition is filed, and that the tariff did not address what happens after the petition is filed with the Commission. Thus, the court reasoned, the tariff is really not central to the issue currently before the Commission. - Rather, the docket is concerned with how the Commission will decide the FPOS issue.
B. The Commission Reasonably Concluded that AECA Does Not Qualify for Express or Implied Mandatory Intervention.
AECA concedes it has no express statutory right to intervene, but asserts that a regulated entity is automatically given party status in a proceeding in which its own tariff is at issue without the need to intervene at all. AECA relies on § 608(b) of the Commissions access charge manual and § 1.3 of AECAs tariff to support this assertion. AT & T contends that the access charge manual and relevant statutory and regulatory authority evince a narrow role for AECA, focused exelusively on assessing, collecting, and distributing access charges. GCI and the Commission make similar arguments.
AECAs argument fails because its role is essentially that of an administrator. The Alaska Public Utilities Regulatory Act authorized the Commission to form an association to assist in administering the system of access charges. When the Commission created AECA in 1989, it stated:
[We believe] that organization of an ECA will be of significant benefit in the development, implementation, and administration of access charges. The ECA will have primary responsibility for preparing, filing, and supporting the single, statewide average access charge tariff required by the Commission and for recommending ratios for distributing resultant revenues to the LBECs. Further, the ECA will handle the functions of collecting the approved rates and distributing the carrier access revenues pursuant to the approved distribution ratios and other applicable Commission rules. The ECA will also have monitoring report filing responsibilities and other obligations to its members....
None of the foregoing functions of the ECA involve any delegation by the Commission of its duties and powers. The Commission, not the ECA, will approve tariffs for, and rules governing, access charges and ratios for appropriate distribution of access charge revenues among LECOs.
A change in FPOS relates to AECAs tariff only in the sense that AECA will need to prepare, file, and distribute a revised access charge. - The statute authorizing AECAs creation explicitly refers to AECAs role in administering access charges. The tariff language states that AECAs role is limited to billing and collecting access charges, distributing access charge revenues, and similar functions. The Commission expressly stated that it did not cede any of its duties or powers to AECA. Thus, although AECAs tariff is at issue in the sense that it provides the context for the proposed change in FPOS, AECAs role as an administrator is insufficient to warrant automatic party status in the proceeding.
AECA contends that proceedings before the Commission involved considerable evidence on the proper application and interpretation of AECAs tariff and that evidence concerning the proper interpretation and application of AECAs FPOS provisions was actually introduced in the underlying docket over the objections of GCI and AT & T. Interpretation of the tariff was at issue in those proceedings only insofar as ITC unsue-cessfully argued that the tariff contained standards relevant to the Commissions decision on the proposed FPOS change. The Commission flatly rejected this argument, noting that the tariff merely provided for alternative dispute resolution procedures for a proposed FPOS change, and that [olncee a petition is filed, the role of the tariff ends. Because the tariff was not actually at issue, the Commissions decision that AECA did not have an implied statutory right to participate in the proceedings is reasonable in light of AECAs narrow administrative role.
AECA also asserts that its authorized activities are nearly identical to those of the National Exchange Carrier Association (NECA). - The Federal Communications Commission (FCC) has stated that NECA may freely express its views before [the FCC] whenever it chooses to do so and that it would be an error to restrict ... the free expression of NECAs views in proceedings before the FCC. NECAs role as an administrator is indeed analogous to that of AECA. A National Regulatory Research Institute report on NECA lists NECAs purposes as filing common access charge tariffs for exchange carriers, administering access charge revenue pools, and distributing the pool revenues. Regarding legal matters, the report states: "NECAs functions are confined to those activities related to the development and filing of access charges and the collection and distribution of access charge revenues, including involvement in related judicial and regulatory proceedings. Any other activity is prohibited unless prior Commission approval has been granted. Title 47 of the Code of Federal Regulations supports the reports characterization:
Section 69.608 Association functions.
(a) [NECA] shall not engage in any activity that is not related to the preparation of access charge tariffs or the collection and distribution of access charge revenues or the operation of a billing and collection pool on an untariffed basis unless such activity is expressly authorized by order of the [FCC]. (b) Participation in [FCC] or court proceedings relating to access charge tariffs, the billing and collection of access charges, the distribution of access charge revenues, or the operation of a billing and collection pool on an untariffed basis shall be deemed to be authorized [NECA] activities.
However, AECAs reliance on NECA is unpersuasive for two reasons. First, the authority AECA cites does not expressly provide NECA an unfettered right to intervene as a party in all regulatory proceedings involving its members that may touch upon its tariff, nor have we found any such authority. Second, the Commission is not bound to follow the FCC. Thus the Commission had a reasonable basis for concluding that AECA may not intervene as a matter of right: no statute expressly provides for such a right, and no implied right exists because AECAs role is limited to administering the system of access charges.
C. The Commission Was Within Its Discretion To Deny AECA Permissive Intervention.
AECA asserts that it meets the permissive intervention criteria set out in 8 AAC 48.110(a) and (b). Specifically, AECA claims that: (1) it has a direct interest in the tariffs interpretation and application; (2) any Commission ruling concerning the tariff will impact it and its members; (8) only through intervention can it protect its interests; (4) no other party can represent its unique interest or present its unique perspective; (5) its institutional knowledge about development of § 2.6 of the tariff will assist in developing a complete record; and (6) far from intending to broaden the issue or delay proceedings, it already had timely filed testimony and agreed to an expedited procedural schedule.
Our inquiry is limited to whether the Commissions application of the permissive intervention factors to the facts of this case was arbitrary, unreasonable, or an abuse of discretion. Although the Commissions initial ruling was limited to analogizing this case to Docket U-99-81, in denying reconsideration the Commission explicitly stated that AECA failed to satisfy the second, sixth, and seventh permissive intervention factors. It found AECAs claimed interest in the interpretation and application of its tariff was insufficient, and although its members property or financial interests may qualify them for intervention, AECA as an organization has not demonstrated such a property or financial interest. Additionally, the Commission found AECAs institutional knowledge about adoption of § 2.6 of the tariff would not assist in developing a sound record and intervention on the part of AECA to provide this institutional knowledge may delay the proceeding. Those findings are not clearly erroneous, and based on those findings, the Commission reasonably denied AECAs petition to intervene.
v. CONCLUSION
Because the Commission reasonably concluded that AECA does not qualify for mandatory intervention under 3 AAC 48.110, and because the Commission did not abuse its discretion in denying permissive intervention under that regulation, we AFFIRM the denial of AECAs intervention in the underlying regulatory proceeding.
. See, eg., Alaska Pub. Util. Commn, Re Intrastate Access Charges & Subscriber Line Charges, 10 A.P.U.C. 34, 36-37 (1989).
. Id.
. See id. at 39.
. Id. at 38. AS 42.05.830 provides for the establishment of a system of access charges to be paid by long distance carriers to compensale local exchange carriers for the cost of originating and terminating long distance services.
. Id. at 37.
. Id. at 39. In Alaska, a tariff specifies the terms and conditions under which a utility offers services to the general public. AS 42.05.990(7).
. Newtows Terecom Dictionary 393 (22d ed.2006).
. 3 Alaska Administrative Code (AAC) 48.110(a) (2008) provides:
Petitions for permission to intervene as a party will be considered only in those cases that are to be decided upon an evidentiary record after notice and hearing. Any person who has a statutory right to be made a party to that proceeding will be permitted to intervene. Any person whose intervention will be conducive to the ends of justice and will not unduly delay the conduct of the proceeding will, in the commissions discretion, be permitted to intervene.
. GCI Commen Corp. v. Tel. Utils. of the North-land, Inc., Docket U-99-81, Order No. 1, at 12 (Regulatory Commn of Alaska, Nov. 1, 1999).
. E.g., Cook Inlet Pipe Line Co. v. Alaska Pub. Utils. Commn, 836 P.2d 343, 348 (Alaska 1992) (citing Tesoro Alaska Petrol. Co. v. Kenai Pipe Line Co., 746 P.2d 896, 903 (Alaska 1987)).
. Tesoro, 746 P.2d at 903 (citing, eg., Matanuska-Susitna Borough v. Hammond, 726 P.2d 166, 175-77 (Alaska 1986)).
. Id.
. Id.
. Griffiths v. Andys Body & Frame, Inc., 165 P.3d 619, 623 (Alaska 2007) (quoting Hodges v. Alaska Constructors, Inc., 957 P.2d 957, 960 (Alaska 1998)).
. Matanuska Elec. Assn, Inc. v. Chugach Elec. Assn, Inc., 53 P.3d 578, 583 (Alaska 2002) (citing Tlingit-Haida Regl Elec. Auth. v. State, 15 P.3d 754, 761 (Alaska 2001)).
. Amerada Hess Pipeline Corp. v. Regulatory Commn of Alaska, 176 P.3d 667, 673 (Alaska 2008) (citing Alyeska Pipeline Serv. Co. v. DeShong, ¶7 P.3d 1227, 1231 (2003)).
. Docket U-99-81, supra note 9, at 12.
. Id. at 10, 12.
. Id. at 7.
. See id. at 17.
. Id. at 16-17.
. Regulatory Commn of Alaska, Alaska Intrastate Interexchange - Access Charge Manual § 603(b) (2006) available at <http://www.alaska. net/aeca/AIIACM-June 14, 2006.pdf>. The manual provides: Participation in Commission or court proceedings relating to the Associations access charge tariff, the billing and collection of the Associations access charges, or the distribution of the Associations access charge revenues shall be deemed to be authorized Association activities.
. Alaska Pub. Util, Commn Access Services Tariff 999 § 1.3 (1997), provides that AECA has the primary responsibility for preparing, filing, and supporting this tariff; billing and collecting access charges; handling disputes; and distributing access charge revenues to the individual companies.
. AS 42.05.
. AS 42.05.850 provides: The commission may require the local exchange carriers to form an association to assist in administering the system of access charges and may require the association to file tariffs and to engage in pooling of exchange access costs and revenue if necessary.... A local exchange carrier is any carrier certificated to provide local telephone services. AS 42.05.890(1).
26. Intrastate Access Charges, supra note 1, at 39.
. See AS 42.05.850.
. Intrastate Access Charges, supra note 1, at 39.
. AECA claims that § 2.6 of its tariff authorizes intervention. But that section merely requires local telephone companies to give the Commission and access customers notice of any proposed changes to the FPOS and delineates the process by which access customers may object to proposed changes. Access Services Tariff, supra note 23 at § 2.6(A-F).
AECA also points to Docket U-00-88, in which the Commission allowed an oil company and two natural gas companies to intervene because [clustomers of a public utility have a statutory right to participate as a party [sic] in utility proceedings" and the companies would have had standing to seek judicial review. In Re Investigation into 2000 Revenue Requirement & Cost of Svc. Studies, Docket U-00-88, Order No. 2 at 4 (Regulatory Commn of Alaska, Feb. 5, 2001). Docket U-00-88 is distinguishable from this case because AECA is not a customer of a public utility.
. - In Re Petition Filed by Interior Tel. Co., Inc. to Implement a Proposed Network Change Under Alaska Exchange Carriers Assn, Inc., Tariff Section 2.6(f}, Docket U-06-109, Order No. 10 at 3 (Regulatory Commn of Alaska, June 6, 2007).
. Id. at 4.
. In re Amendment & Clarification of Part 69 Rules Governing the Natl Exch. Carrier Assn, 2 F.C.C.R. 381, 382 (1987).
. - Jang L. Racster, Nart Recutatory ResEarck Inst., Tes Nart Exc. Carrier Assn: Structure anp Operation, 1-2 (1985).
. Id. at 10.
35. 47 C.F.R. § 69.603(a)-(b) (2007).
. See 2 F.C.C.R. at 381-85.
. But see, eg., In re CF.Commens Corp. v. Mich. Bell Tel. Co., 12 F.C.C.R. 2134, 2144 (1997) (granting NECA leave to intervene as ami-cus curiae).
. Griffiths, 165 P.3d at 623 (quoting Hodges v. Alaska Constructors, Inc., 957 P.2d 957, 960 (Alaska 1998)).