First things first: the idea that women are inherently excluded from serving in positions of leadership demands that the burden of proof be placed on people who prefer to exclude them. The nature of New Testament theology makes excluding people who are not in sin a very rough paradigm to assert. Sin is a disqualifier, certainly, but gender?
1. Phoebe in Rom 16:1-2
Many English translations water down this text. Phoebe is described as διάκονον τῆς ἐκκλησίας τῆς ἐν Κεγχρεαῖς, which is roughly translated to "deacon [perhaps the deacon] of the church in Cenchrea." The fact that is spoken about as a "deacon" at a specific church tells us she is highly involved in that assembly. It also states that Rome is not her local church, as Cenchrea is a fair distance from Rome: so she had the means and resources to make it, without a husband named, from that area to Rome. The word διάκονον is semantically unrelated to the common word for slave, which is δοῦλος. So the idea of rendering this term as "servant" is lexically and linguistically false.
Paul also describes her as a προστάτις is used to describe presidents of an association (O. Tebt. Pad. 67), and likely means that here. Hence, Phoebe was involved in leadership of Cenchrea, and since no other leadership is named, we are on good grounds to take her as "the" deacon of the church. It would have been easy for Paul to say, "Phoebe…who is under the authority of this dude in Cenchrea." But he doesn't. Hence, Phoebe is a deacon/leader in the church and probably, based on the context, was involved in leadership (or as the leader over) the church. In Greco-Roman literature, the word προστάτις referred to "leadership," "benefaction," "protector," "champion" (LSJ). So translating the language as "servant" is simply untenable. Phoebe was an actual deacon and was most likely, based on the context and the words Paul uses to describe her, was a leader of many and even of Paul (ἐμοῦ: "of me" in Rom 16:2b).
2. Women Deacons in 1 Tim 3:8-12
Paul speaks of "deacons in this way being noble" (Διακόνους ὡσαύτως σεμνούς: 1 Tim 3:8) and says virtually the same thing in 3:11 (γυναῖκας ὡσαύτως σεμνάς).
The lack of a personal pronoun identifying γυναῖκας as "wife" (as in, "their wife") is rather decisive: the person in view is a woman, not specifically a wife. A woman is given the same qualification as the "deacon" in 3:8, and are included in the same linguistic sphere. The phrase "one woman man" (μιᾶς γυναικὸς ἄνδρες) refers to monogamy, not the fact that the deacon/elder must be male. Leading complementarians affirm this point that monogamy is in view, not the 'male' only aspect that many prefer to see. The use of the adverb "likewise" (ὡσαύτως) indicates continuity: vv.8-11 are following on the principles argued in 1 Tim 3:1-7, where "anyone" (τις) is encouraged to seek leadership. Hence, women are not excluded from the office of deacon nor are they (I would argue) excluded from ministerial positions at all. Thus, the lack of a definite article or personal pronoun in relation of "women" indicates that women deacons are in view in 3:11 and male deacons are in view in 3:8. Both are treated equally as it relates to virtue and so forth.
The following points are intended to communicate the egalitarian nature of New Testament theology. Our theology of baptism is affirming of women as equal participants in the community of faith, in participation in Christ (Gal 3:26-29). Baptism is a sign of the new life, and male and female are not shown partiality in this endeavor (1 Cor 12:13).
Justification by faith is an aspect that gets overlooked here. Men and women are justified on the same grounds: faith/allegiance to Christ, which is significant insofar as women are not excluded from participating in what Christ has called them to. Men and women are made right by God together with any notion of hierarchy or that God justifies men and women any differently (Rom 5:18). Faith is the primary relational component of justification and faithfulness is not applied to any specific gender exclusively.
5. Spiritual Gifts
The Holy Spirit sovereignly gives gifts for everyone without regard to gender. This includes "the one who leads" (προϊστάμενος: Rom 12:8, where the context is not gender-specific or exclusive), as well as specific ministerial positions of leadership (ἔδωκεν τοὺς μὲν ἀποστόλους, τοὺς δὲ προφήτας, τοὺς δὲ εὐαγγελιστάς, τοὺς δὲ ποιμένας καὶ διδασκάλους: Eph 4:11). Nowhere in either text is any hint of male-only giftedness to serve in ministerial leadership.
6. Church History
Jamin Hübner has decisively shown that women deacons were part of early church history. It is noteworthy that Pliny the Younger in 112 AD tortured "two maidservants who were called deaconesses [ministrae]" (Epistle X, 96.8). The point is that Pliny identified the women as slaves, but they were called ministrae by the local assembly, which is more accurately translated as "minister" or "deacon."
People love to use nebulous terms like "roles," but such language is undefined and culturally-bound by the present. Such language was not used until very recently. We know women exercised authority in prophesy (1 Cor 11:2-16, which affirms biological distinctions but not biological hierarchy), leadership (Phil 4:2-3), apostleship (Rom 16:7), and significant work in Christ (Rom 16:3-6, 8ff, where a lot of women are named alongside men without any indication of hierarchy). All of this evidence, among much more that I could mention, tells us that Scripture is clear about what women are called to be in Christ, and that involves every aspect of New Testament theology and the two texts that are relevant.