Levine, J.,
delivered the opinion of the Court. Barnes and Digges, JJ., concur in part and dissent in part and Barnes, J., filed an opinion concurring in part and dissenting in part in which Digges, J., concurs at page 96 infra.
Although shrouded in a mass of technical evidence dealing with the complex subject of mobile radio communications, the primary question presented by this case is simply one of legislative intent. This appeal is brought by Radio Communications, Inc. (RCI) — a “radio common carrier” — from an order of the Circuit Court for Prince George’s County affirming a decision of the Public Service Commission of Maryland (the Commission), one of several appellees. The remaining appellees (the intervenors) are also radio common carriers who initially entered this case by intervening in the proceedings before the Commission.
Prior to July 1, 1971, radio common carriers were not [84]*84regulated in the State of Maryland. In that year, the General Assembly enacted Chapter 543 of the Laws of 1971 — the source of this controversy — which brought companies engaged in that field of communications under state regulation for the first time. This resulted in dual control, since the medium had already been under the jurisdiction of the Federal Communications Commission (FCC) prior to 1971.
Chapter 543 achieved a threefold purpose, all within the framework of Maryland Code (1957, 1973 Cum. Supp.) Art. 78. First, it amended § 2 (o) of Art. 78, so as to embrace “radio common carrier[sj” within the definition of “ ‘public service companies].’ ” Second, it added a subsection (ii) to § 2, defining a “ ‘Radio common carrier’ ” as:
“. .. every public service company operating or managing a radio common carrier engaged in the business of providing a service of one-way or two-way radio communications and licensed as a miscellaneous common carrier by the Federal Communications Commission, but not engaged in the business of providing a public land line message telephone service or a public message telegraph service. The terms ‘telegraph company,’ ‘telephone company,’ or ‘a person operating telegraph or telephone lines’ when used in this article, shall not be construed to include radio common carriers.”
Third, Chapter 543 added § 55A to Art. 78. This is the vehicle by which such carriers were for the first time brought under state regulation. Since they are material to the disposition of this case, we repeat here subsections (a), (b) and (d) of § 55A:
“(a) When certificate required; rules and regulations. — No radio common carrier shall begin or continue the construction or operation of any radio common carrier system or any extension thereof, either directly or indirectly, without first obtaining from the Commission a certificate that the public convenience and necessity required such [85]*85construction, operation or extension. However, this article shall not require nor shall it be so construed to require any carrier to secure a certificate for any of the following:
“(1) An extension within any authorized service area within which the carrier has heretofore lawfully commenced operations, (2) any extension within or to territory already served by the carrier, necessary in the ordinary course of business, (3) substitute facilities within or to any authorized service area or territory already served by such carrier, (4) any extension into territory contiguous to that already served by the carrier and not receiving similar service from another carrier when no certificate of convenience and necessity has been issued to or applied for by any other radio common carrier, and (5) the acquisition, construction and operation of any plant or system heretofore constructed under authority of a certificate of convenience and necessity hereafter issued. The Commission is authorized to prescribe appropriate and reasonable rules and regulations governing the issuance of the certificates.
“(b) Certification of carriers licensed by Federal Communications Commission. — Any company not presently franchised or certificated by the Commission as a radio common carrier but engaged in the operation of any radio common carrier system licensed by the Federal Communications Commission on July 1, 1971, shall, upon qualification as a public service company receive a certificate of convenience and necessity from the Commission authorizing the company to continue the operation of the radio common carrier in the territory professed to be served by tha+ company on July 1, 1971, if, within ninety days after this act becomes effective, that company shall file with the [86]*86Commission an application for the certificate, including copies of any license or licenses issued by the Federal Communications Commission to that company, showing the area professed to be served by that company.
“(d) Duplication of or competition with existing services. — The Commission shall not grant a certificate for a proposed radio common carrier operation or extension thereof into the established service area which will be in competition with or duplication of any other certificated radio common carrier unless it shall first determine that the existing service is inadequate to meet the reasonable needs of the public and that the carrier operating the same is unable to, refuses or neglects, after hearing on reasonable notice, to provide reasonably adequate service.” (emphasis added).
The evidence discloses that mobile radio communications is a rapidly expanding branch of the communications field. Essentially, radio common carriers provide a mobile communications service, either by two-way transmission or one-way signalling. They operate base stations at which are located transmitters and receivers. The control point or message center, however, is the actual hub of the operation. The carrier operates its transmitters and receivers on channels or frequencies assigned by the FCC within a band allocated for that purpose. In Maryland, there are only two instances of co-channels, an arrangement under which a single radio frequency is shared by two or more radio common carriers. RCI participates in one of those co-channels. They are permitted by the FCC when agreed to by the participants.
Those who subscribe to a mobile communications service purchase or lease a mobile radio set, which may include a transmitting and receiving device for two-way communications or simply a receiver if only a one-way signalling service is desired.
[87]*87Prior to 1971, radio common carriers were regulated only if they provided services utilizing “interconnections” with “land line” telephone systems. The most frequently cited illustration of hew this interconnection operates is the placement of a call from a subscriber’s office to one of its mobile units in the field. The caller, by a regular telephone call, reaches the control point operated by the radio common carrier, which then completes the call to the mobile unit by radio. Although there are calls made completely by radio, for example, from one mobile unit to another, it is apparent that the “interconnection” with regular telephone systems is the most prominent phase of this communications field.
It is this interconnection with land line telephone systems that first brought radio common carriers under limited scrutiny of the Commission. Even prior to 1971, radio common carriers were required to obtain Commission approval of services utilizing such interconnections. Thus, shortly after its formation in 1960, RCI applied to the Commission for the right to exercise its “franchise” in the seven counties in which it was then operating as a radio common carrier: Anne Arundel, Calvert, Charles, Howard, Montgomery, Prince George's and St. Mary’s. In March 1963, the Commission issued an order authorizing RCI “to exercise franchises and rights, including the franchise granted to the said company by its certificate of incorporation for the operation of a radio communications system in the State of Maryland ... as and to the extent set forth and described in this proceeding.” 1
After Chapter 543 became effective, the Commission held a hearing on August 4, 1971, following which, pursuant to [88]*88the authority expressly conferred by § 64 of Art. 78 and subsection (a) of § 55A, it promulgated by an order dated September 27, 1971, “. . . rules and regulations [effective September 29, 1971] governing the issuance of certificates of public convenience and necessity for radio common carriers under Section 55A . . . .” Pursuant to those rules and § 55A, RCI and other radio common carriers — including intervenors — promptly filed applications for certificates of public convenience and necessity.
In its application, RCI sought to exercise a franchise for the following political subdivisions of the state: the City of Baltimore and the counties of Anne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles, Caroline, Dorchester, Frederick, Harford, Howard, Montgomery, Prince George’s, Queen Anne’s, Somerset, St. Mary’s, Talbot, Washington and Wicomico. The intervenors took a rather dim view of this preemptive bid and, regarding it as a flagrantly expansionist move by RCI, leaped into the affray. Several hearings ensued, which were characterized by polemics on the part of the protagonists and admirable restraint on the part of the Commission. Thus, merely two witnesses managed to produce three substantial volumes of testimony.
The sole witness who testified for RCI was its president, Boyd King (King); and for the intervenors, John E. Dettra, Jr., (Dettra), a radio engineer. Since most of this evidence is not material to the disposition of this appeal, no useful purpose could possibly be served by an extensive summary of the testimony. Indeed, because of its highly technical nature, merely undertaking a limited review presents a formidable task.
In brief, King testified that RCI operated five base stations on July 1, 1971, two at Bethesda, and one at each of the following sites: Prince Frederick, Upper Marlboro, and Annapolis. For each of those locations, maps were introduced with circles depicting the area in which RCI transmitted and received radio communications to and from mobile units. King emphasized that these circles were drawn on the basis of where RCI could “put” a signal and could communicate with mobile units from the particular base [89]*89station encircled on the map. In this manner. RCI transmitted and received signals as a radio common carrier on July 1, 1971, in each of the 21 subdivisions for which it was seeking certification. King explained that RCI’s operations had expanded from the seven counties approved in the telephone interconnection context by the 1963 Commission order, mainly because of its improved technical facilities. These consisted of a change from low to high power transmitters and significant increases in antenna height.
The role of the FCC in regulating radio common carriers was explained by King: He stated that the purpose of the FCC license issued to such carriers is limited to the approval of the construction and operation of transmitters and companion mobile units. In other words, the license simply confers authority to establish and operate a base station at a particular site. Once the license is issued, the FCC permits licensees to operate wherever their signal penetrates. In short, according to King, under the FCC license, the carrier may broadcast or receive within a territory defined solely by the capability of its equipment and antennae. An “effective signal” was described by King as one which permits the base station to reach by radio a subscriber in a mobile unit within the area designated on each of the maps.
Needless to say, intervenors vigorously dispute these claims; indeed, their entire approach to this case, including the testimony of Dettra, varies sharply from the premise on which RCI presented its case. Their position was ultimately adopted by the Commission in reaching its decision.
The gravamen of Dettra’s testimony is a standard called the “reliable service area” of a radio common carrier. It is determined by a plotted contour line known as 37 DBU (decibel units); this delineates an area in which service is generally expected to have an average reliability of not less than 90 per cent. This standard originated in a study that is commonly referred to as the “Boese Report,” prepared for the FCC in 1951 by one of its engineers.2
[90]*90This testimony by Dettra was accompanied by a series of maps on which are drawn the 37 DBU contours for each of the base stations operated by RCI. Dettra explained that under FCC policy, the base station of a radio common carrier is expected to be within the toll-free telephone area of the community which it serves, so that the subscriber and the public generally may gain access to the transmitter by non-toll telephone calls.
In sum, although the intervenors conceded that the effective range of the RCI transmitters might sporadically extend beyond the 37 DBU contour, Dettra’s thesis was that beyond this area, the signal would not meet the 907 reliability test fostered by the FCC. For this reason, he testified, RCI cannot render “reasonably adequate” service in each of the entire 21 subdivisions for which it requests certification. He did concede that it could do so in parts of the counties of Dorchester, Frederick, Kent, Queen Anne’s, Talbot and Wicomico, in addition to the seven counties which it had already served since 1963.
As we have indicated, the Commission basically adopted the test advanced by Dettra in passing its order of February 9, 1972. It ruled that it was required to grant “grandfather” rights under subsection (b) of fj 55A to radio common carriers licensed by the FCC “where they were legally rendering service adequate to meet the reasonable needs of the public on the effective date of the Act.” (emphasis added).
Thus, the Commission found:
“(2) That for the sole purpose of establishing the reliable service area of a radio common carrier public service company pursuant to Section 55A of Article 78, the Commission should consider the FCC prescribed decibel contour of a company’s station plus a deviation of five (5) statute miles beyond said contour.
“(3) That the Commission should consider the reliable service area so determined as the only area in which a Radio Common Carrier may render a [91]*91satisfactory service, free of electrical inference [sic] or competitive economic injury, subject to the following conditions:
“(a) service to existing customers will not be impaired by the service area so determined.
“(b) customers garaged in an area of overlap between two or more carriers mil have the benefit of service from such carriers.
“(c) the service area should not in any way limit or restrict the carrier of radio communications by telephone.
“(d) the carriers should formulate a mutual agreement whereby the user of a mobile radio telephone who travels within a particular county or counties or throughout the State would not be restricted of normal communication.
“(4) That the reliable service area of Radio Communications, Inc., is as follows:
In its entirety:
Montgomery County
Calvert County
Prince George’s County
St. Mary’s County
Portions of the following Counties in Maryland, in accordance with the delineations on mays which are on file with this Commission:
Howard County
Anne Arundel County
Kent County
Queen Anne’s County
Talbot County
Dorchester County
Charles County” (emphasis in original).
This order was affirmed on appeal to the circuit court which followed the lead set by the Commission in applying the “reasonably adequate service” standard contained in Art. 78, § 55A (d) to RGBs application, which, however, was [92]*92filed pursuant to § 55A (b). The court also took note of the Commission’s “special type of expertise” and held that its decision was not “arbitrary, capricious or illegal.”
The Commission’s decision is attacked by RCI on these grounds:
(1) The first, and by far the primary, contention urged for reversal is that the Commission erred in ignoring the simple requirement set forth in (b) for “grandfather” carriers, “the territory professed to be served”; and instead engrafted upon subsection (b) the test contained in (d), which is applicable only to “proposed” carriers.
(2) Even assuming that the Commission applied the correct test, its decision is “unsupported by substantial evidence on the record considered as a whole” and is therefore arbitrary and capricious.
(3) That the Commission “erred in failing to award” RCI “the entire counties in which it was previously certificated.”
(4) The Commission erred in “apparently” attaching certain conditions to the certificate which it did grant.
In the view we take of this case, it is necessary that we reach only the first issue.
In arguing that the Commission failed to interpret subsection (b) of § 55A correctly, and thus applied an improper test for a “grandfather” application filed thereunder, RCI maintains that it met the requirements of (b) by merely “professing to serve” the 21 subdivisions for which it sought a certificate. But it also contends that it actually proved it did serve those 21 subdivisions; and that this evidence was not contradicted.
The intervenors, on the other hand, argue not implausibly that the legislature never intended that a carrier seeking “grandfather” rights could obtain them by simply making a bald assertion that it “professed” to serve the area being sought. Yet, while acknowledging that this case is controlled by subsection (b), they also argue that, as set forth in (d) for proposed carriers, RCI should receive a certificate only for [93]*93those areas where it could provide service adequate “. . . to meet the reasonable needs of the public . . . .” Hence, they maintain, since the “reliable service area of a radio common carrier” — Dettra’s test for meeting those “needs” — is established by the 37 DBU contour, RCI is not entitled to a certificate beyond those limits.
We think the disposition of this case lies between these respective contentions. Although we find ourselves lacking complete agreement with either position, we are of the view that the Commission — and, hence, the circuit court in affirming it — applied an incorrect standard, and thus erred in its interpretation of § 55A.
What the legislature intended as the standard for carriers seeking “grandfather” rights under § 55A (b) must be determined in the first instance by a careful examination of the statute itself, since the cardinal rule of construction is to ascertain and carry out the real legislative intention, Scoville Serv., Inc. v. Comptroller, 269 Md. 390, 393, 306 A. 2d 534 (1973); Silberman v. Jacobs, 259 Md. 1, 267 A. 2d 209 (1970); Atlantic, Gulf v. Dep’t of Assess. & T., 252 Md. 173, 249 A. 2d 180 (1969); Equitable v. Insurance Comm’r, 251 Md. 143, 246 A. 2d 604 (1968); and in ascertaining that intention, the Court considers the language of an enactment in its natural and ordinary signification, Germenko v. Pub. Service Comm., 226 Md. 295, 301-02, 173 A. 2d 362 (1961); Height v. State, 225 Md. 251, 257, 170 A. 2d 212 (1961). Thus it is necessary and proper to construe a statute only when it is ambiguous and of doubtful meaning, Scoville Serv., Inc. v. Comptroller, supra; Hunt v. Montgomery County, 248 Md. 403, 237 A. 2d 35 (1968); Falcone v. Palmer Ford, 242 Md. 487, 219 A. 2d 808 (1966). If there is no ambiguity or obscurity in the language of a statute, there is usually no need to look elsewhere to ascertain the intent of the legislature, Scoville Serv., Inc. v. Comptroller, supra; Maryland Nat’l Bk. v. Comptroller, 264 Md. 536, 287 A. 2d 291 (1972); Atlantic, Gulf v. Dep’t of Assess. & T., supra; Department v. Greyhound, 247 Md. 662, 234 A. 2d 255 (1967); Md. Medical Service v. Carver, 238 Md. 466, 209 A. 2d 582 (1965).
It is immediately apparent that § 55A is a carefully [94]*94conceived statutory scheme for the regulation of all radio common carriers in Maryland. Likewise, it is plain that subsection (b) was intended to regulate the issuance of certificates to all such carriers who were “engaged in the operation of any radio common carrier system licensed by the Federal Communications Commission on July 1, 1971,” otherwise known as “grandfather” carriers.
It is equally clear that those seeking certificates who do not meet the requirements of subsection (b) for “grandfather” status, must file an application as a “proposed” carrier under (d). Should a carrier be certificated under (b) and then be challenged by a “proposed” carrier asserting “inadequate” service on the part of the “grandfather” carrier, the standard in (d) must then be invoked.
It follows that the legislature, having opted for this dichotomy in the statutory scheme, intended entirely separate tests for certification under the two subsections. The statutory distinction would completely lose its significance if a carrier operating prior to July 1, 1971, were expected to meet the same standard as that confronting a “proposed” carrier.
By reading into subsection (b) the standard set forth in (d), the Commission erred in undertaking to insert words in (b) which, in our view, were deliberately omitted by the legislature. Construing a statute liberally and adding to it, by judicial fiat, a provision which the legislature did not see fit to include are not one and the same thing, Real Estate Comm’n v. Phares, 268 Md. 344, 348, 302 A. 2d 1 (1973); Amalgamated Ins. v. Helms, 239 Md. 529, 212 A. 2d 311 (1965). As a general rule, a court may not surmise a legislative intention contrary to the plain language of a statute, nor insert or omit words to make the statute express an intention not evidenced in its original form, Amalgamated Ins. v. Helms, supra at 535; see also Pressman v. State Tax Commission, 204 Md. 78, 102 A. 2d 821 (1954).
Therefore, in the absence of ambiguity, the Courts should, as a general rule, confine themselves to a construction of a statute as written, and not attempt, under the guise of construction, to supply omissions or remedy possible defects [95]*95in the statute, or to insert exceptions not made by the legislature, Scoville Serv., Inc. v. Comptroller; Amalgamated Ins. v. Helms, both supra. As so aptly stated by Justice Brandéis in Iselin v. United States, 270 U.S. 245, 251, 46 S. Ct. 248, 70 L. Ed. 566 (1926):
. . What the Government asks is not a construction of a statute, but, in effect, an enlargement of it by the court, so that what was omitted, presumably by inadvertence, may be included within its scope. To supply omissions transcends the judicial function
In addressing themselves to the question of what standard was intended by the legislature in enacting subsection (b), the parties have cited a number of our prior decisions involving appeals from the Public Service Commission, including several in which we have touched on the subject of “grandfather” rights in other categories. The difficulty which stems from relying upon those authorities is that in none of them were we dealing with statutory language similar to that confronting us here.
RCI claims it is sufficient for purposes of obtaining “grandfather” certification in the 21 subdivisions if it merely “professes” to serve them. Appellees argue, with considerable logic, that this would reduce the Commission’s role in this proceeding to that of a “rubber stamp.” We agree that while the standards in (d) do not apply, RCI must nevertheless do more than merely “profess” to serve. It contends, however, that it did so by proving that it had communicated with mobile units in the 21 subdivisions from one or more of its base stations; and that this testimony was not effectively disputed by any of the intervenors.
We read subsection (b) to say that those who assert “grandfather” status cannot obtain certification by merely “professing to serve” a given area or county. Subsection (b) provides for certification of a radio common carrier “engaged in the operation of any radio common carrier system . . . .” By obtaining certification, a carrier is expected “. . . to continue the operation ... in the territory professed to be served . . . .” (emphasis added). Thus, when [96]*96the application of a subsection (b) radio common carrier professing to have served an area is challenged, that carrier must then prove that, in fact, it did serve that area, i.e., that on July 1, 1971, it was “engaged in the operation” of a radio common carrier system in each subdivision for which certification is sought. As we have already held, that requirement may not be embellished with any other standard not found in the language of subsection (b) itself. All parts and sections of a statute must be read and considered together in arriving at the true intention of the Legislature since they form part of a general system or scheme. Parker v. Junior Press Printing, 266 Md. 721, 725, 296 A. 2d 377 (1972); Height v. State, 225 Md. 251, 257, 170 A. 2d 212 (1961); Thomas v. Police Commissioner of Baltimore City, 211 Md. 357, 361, 127 A. 2d 625 (1956); State v. Petrushansky, 183 Md. 67, 71, 36 A. 2d 533 (1944).
Although RCI did endeavor to furnish the proof required by (b), the Commission was preoccupied with the premise that the subsection (d) standard controlled. We think the case should be remanded to the Commission for further proceedings, including the introduction of such additional evidence as the Commission may require, in order that RCI may be afforded the opportunity of establishing in what areas it did actually provide service, and for which it seeks certification under subsection (b); and so that intervenors may have the opportunity to present contrary evidence. In so ' holding, we carefully refrain from expressing any opinion on whether the 37 DBU contour is a proper standard for “proposed” carriers seeking certification under subsection (d).
Order reversed; remanded for further proceedings before the Public Service Commission of Maryland; costs to be paid equally by appellees.