delivered the opinion of the court.
This case is here on a petition for a writ of certiorari by petitioner, the City and County of Denver, against respondents, the Public Utilities Commission of the State of Colorado and its individual members, and the Mountain States Telephone and Telegraph Company, a Colorado corporation, to review the findings and judgment of the District Court of the City and County of Denver, which had approved an order of the Public Utilities *43Commission granting a tariff rate increase. The parties appear here as in the trial court and will be designated as Denver, Commission and Company.
On May 6, 1952, after a hearing thereon, the Commission fixed the fair value of the Company’s Colorado property as of January 31, 1952 at $58,568,550 and ruled it entitled to a fair return of 6.35% thereon, and for $5,579,410, or 19.95% over and above the total intrastate operating revenues for the year as the increase in revenue to which the Company was entitled to enable it to realize such fair rate of return, Decision No. 38593. Thereafter on May 9, 1952 the Company filed with the Commission its proposed schedule of rate increases designated as P.U.C. Tariff No. 4. The Commission suspended the proposed tariff schedule and May 27 to June 3, 1952 held hearings thereon; and June 9 and 20, 1952 entered its order and supplemental order finding the Company’s proposed tariff schedule “just, reasonable, non-discriminatory and non-preferential,” and authorized the rates to become effective forthwith, Decision No. 38836. A petition by Denver for a rehearing was denied. Thereupon Denver filed its petition in the District Court of the City and County of Denver for certiorari and a hearing was had thereon, the court on December 18, 1952 entering its findings and decree affirming the Commission’s order. Denver brings the cause here for review, and asks for a reversal of the judgment.
On review upon certiorari, under Rule 106 (4), R.C.P. Colo., courts are limited in their inquiry as to whether the Commission had exceeded its jurisdiction, had abused its discretion, or had regularly pursued its authority. Public Utilities Commission v. Town of Erie, 92 Colo. 151, 18 Pac. (2d) 906.
The making of rates to govern public utilities is held to be a legislative and not a judicial function. In Colorado that legislative function has been delegated to the Public Utilities Commission. ’35 C.S.A., c. 137, §15; *44People ex rel. Public Utilities Commission v. Mountain States Tel. & Tel. Co., 125 Colo. 167, 243 P. (2d) 397.
The Commission having here found the Company was entitled to additional Colorado intrastate revenues, it became necessary for it to determine how the required earnings should be spread in rates to its various subscribers.
In People ex rel. Public Utilities Commission v. Mountain States Tel. and Tel. Co., supra, this court, overruling its prior decisions, recognized the state-wide basis for the fixing of intrastate telephone rates, and that the Public Utilities Commission is the sole agency authorized to regulate the telephone business and rates in Colorado. The Commission herein followed this “state-wide” basis for rate fixing, and adopted the “value of service” concept therefor. The trial court approved the Commission’s action.
In their briefs the parties discuss the methods of telephone rate making, the “value of service” concept, and the “cost of service” concept. Denver does not here question the “state-wide” basis for rate making, but urges that whatever concept is adopted, it must be based on sufficient, objective, reviewable data, facts and figures therefor. Denver urges that the Commission here had no sufficient evidence for its order, and made no findings thereon, therefore, the Commission’s order was arbitrary, capricious and unreasonable. Denver urges the trial court’s approval of the Commission’s order was error.
The Commission had jurisdiction to determine the applicable intrastate telephone rates and the method of computation therefor. Having previously determined the Company was entitled to a $5,579,410 increase in operating revenue, and approved the rate increase necessary therefor, the sole question now before us is, did the evidence presented support the order of the Commission and the judgment of the trial court?
To sustain its proposed tariff increases the Company *45presented two of its engineers, tariff rate experts, who testified as to the “value of service” concept on a statewide basis, as applicáble to Colorado. They regarded the “cost of service” concept by separated units as inapplicable in the determination of rates. Evidence was presented of the kinds of service and their rates, the differences in kinds of service, the average sizes and types of exchanges, their nature, properties, areas served, the demands for and uses of the several services by groups, their interrelation with other groups, the objectives sought, the insufficiency of revenues, and the rate increases applicable to the several types of service. These facts were related to, and considered in, the rate making decision. The witnesses admittedly base their proposed rate increases on said facts and on their studies, experienced judgment and ultimate opinions. Denver urges the facts so presented did not furnish sufficient, objective, statistical, reviewable data, facts and figures to support the Commission’s order and trial court’s judgment.
Denver’s own rate expert admitted:
“* * * I believe there has never been and never will be devised exact formulas, mathematical or otherwise, upon which a rate determination can be made.” And relative to the value concept, “* * * there is no yardstick of value that has ever been developed, it is only obtained by the exercise of experienced judgment and that is the only practical basis in the application of this component in the development of a rate structure.” The Company’s rate expert similarly testified, “There are no facts, no objective principles, or standards, on which a rate schedule is built.”
The Company experts insist, for rate making, the value of service concept should be followed; that the cost of service studies are limited to the over-all business operation rather than separately, considered for rate purposes. Denver’s rate expert insists otherwise, that the two concepts, cost of service' and value of service, *46“are both important and they both must be given their full consideration in the final determination.” These statements disclose the major difference here urged.
It is apparent that, as to exact statistical data, definite facts and figures to support the specific rate increases', such evidence cannot be had. No rate expert has suggested any such type of evidence, except only a separated cost of service study. The experts differed on the value of such cost studies. Both the Commission and the trial court heard the disputed issue and resolved same for the value of service concept and against the cost concept. Considerable factual evidence of the basis for the rate increases is in the record. To these facts the Company’s rate experts applied their experienced judgment and ultimate opinions. We cannot say the factual evidence here presented was insufficient to support the Commission’s order and the court’s judgment. We will not disturb the trial court’s findings thereon.
On the over-all state-wide basis the Commission found the rates fair, reasonable, non-discriminatory and non-preferential. Whether or not the Commission entered specific findings of fact supporting the exact rate increases becomes immaterial where the record discloses substantial evidence relating thereto. The Commission’s general statement, findings and order here are sufficient. The other alleged errors become immaterial.
The Commission had jurisdiction and there is sufficient competent evidence to support its order. The trial court’s judgment approving the Commission’s order was right.
The judgment of the trial court is affirmed.
Mr. Justice Alter and Mr. Justice Holland dissent.